My trek nation . possible or wank

[FaxModem1]

Maybe he was referring to the Voth, the Telepathic Pitcher Plant, and all the weird anomalies Voyager ran into?

[Borgholio]

Possibly...although the Voth never were that big of a threat. Maybe Q meant it metaphorically, not specifically beyond Borg Space.

[Prometheus Unbound]

Founders / Changelings / Dominion
Species 8472
Voth
Anomalies like in Cause and Effect
Cytherians

[Lord Revan]

or he was lying to make a point that's an option too.

[StarSword]

or he was lying to make a point that's an option too.

That. Q isn't a god to be worshiped, he's an omnipotent Internet troll.

[Tribble]

It's possible that Q was referring to DS9/Voyager's adventures, but IMO it just seems a bit at odds with the context of the episode:

PICARD: Simply speaking, we don't trust you.
Q: Oh. Well, you may not trust me, but you do need me. You're not prepared for what awaits you.
PICARD: How can we be prepared for that which we do not know? But I do know that we are ready to encounter it.
Q: Really?
PICARD: yes. Absolutely. That's why we're out here.
Q: Oh, the arrogance. They don't have a clue as to what's out here.
GUINAN: But they will learn, adapt. That is their greatest advantage.
Q: They're moving faster than expected, further than they should.
PICARD: By whose calculations?
Q: You judge yourselves against the pitiful adversaries you have encountered so far. The Romulans, the Klingons. They are nothing compared to what's waiting. Picard, you are about to move into areas of the galaxy containing wonders more incredible than you can possibly imagine, and terrors to freeze your soul!

IMO it makes more sense Q was referring to the Federation's expansion into that area of the galaxy, rather than the far depths of the Delta/Gamma quadrants. J-25 was only around a 2-3 year journey from the nearest starbase, so it conceivable that the Federation would be expanding into that area within the next decade or two.

PICARD: I understand what you've done here, Q, but I think the lesson could have been learned without the loss of eighteen members of my crew.
Q: If you can't take a little bloody nose, maybe you ought to go back home and crawl under your bed. It's not safe out here. It's wondrous, with treasures to satiate desires both subtle and gross, but it's not for the timid.

You could argue that Q was referring to the galaxy as a whole, but given the earlier context it seems more likely that he was referring to the area around J-25 in particular.

As for Q lying... I don't see why he would do so in this case. Q genuinely seemed to want to join the E-D's crew and was expecting them to agree to it. Only after they refused multiple times did he send them to J-25. Ironically, his actions proved Picard's assertion that he was a harbinger of chaos as he significantly altered the timeline just to satisfy his ego:

GUINAN: Q set a series of events into motion, bringing contact with the Borg much sooner than it should have come. Now, perhaps when you're ready, it might be possible to establish a relationship with them. But for now, for right now, you're just raw material to them. Since they are aware of your existence
PICARD: They will be coming.
GUINAN: You can bet on it.
PICARD: Maybe Q did the right thing for the wrong reason.
GUINAN: How so?
PICARD: Well, perhaps what we most needed was a kick in our complacency, to prepare us for what lies ahead.

[FaxModem1]

Well, I've always liked the interpretation that the whole of Q Who was to get the Federation, Starfleet and Humanity as a whole to realize how relaxed they've become. After all, less than a decade later and they're dealing with a Borg invasion and a war with the Dominion.

If "Q Who" hadn't happened, Starfleet would have been meeting the Dominion with their ancient ships out of mothballs, even more so than we see in the show, and wouldn't have had any designs like the Defiant, Akira, or Steamrunner.

Though, there is the question of whether or not the Dominion War would have even happened. Would the Federation have applied political pressure to the Cardassians to make them release Bajor and discovered the wormhole if the Federation hadn't begun a huge Starfleet build up? Who can say?

[Tribble]

Not only that, but would "the Sisko" have been there to negotiate the prophets to open up the wormhole?

Unlike Q Guinan is not known to be a liar, at least to Picard, and she does appear to be highly sensitive to changes in the timeline. Regardless of his actual motives, it's pretty clear that Q changed things. If the Federation had met the Borg when they were originally supposed to, would they have been ready to establish a relationship? We'll never know for sure, but Guinan seems to imply that would have been the case.

[StarSword]

Though, there is the question of whether or not the Dominion War would have even happened. Would the Federation have applied political pressure to the Cardassians to make them release Bajor and discovered the wormhole if the Federation hadn't begun a huge Starfleet build up? Who can say?

They were supposedly fighting the Cardassians that whole time, so I'd venture to say it's likely.

[Tribble]

They were supposedly fighting the Cardassians that whole time, so I'd venture to say it's likely.

The war ended in a stalemate despite Starfleet's military build-up post Q-Who. Without that buildup I'd say it's more likely that the terms of any agreement would be less in the Federation's favour.

[FaxModem1]

Well, after the big fleet action of Wolf 359, the next one we see is roughly a year later with the Klingon Civil War and Starfleet forming a blockade across the border between the Romulan Empire and the Klingon Empire. As we saw with Data commanding the ship coming out of drydock, the nebula class Sutherland and a few other ships were in a state of repair or construction. If Wolf 359 hadn't happened, would Picard had even been able to scrape up the ships for the blockade? Would the lack of Wolf 359 give them more ships to spare, or would they have too much of a mothballed fleet to even give Picard anything to use?

If not, and with no Wolf 359, this might have led to the Federation being without allies in the Alpha Quadrant as the Romulans control the Klingon Empire.

[Borgholio]

Actually it's mentioned directly in that episode that they are scraping the bottom of the barrel for ships due to the large number lost at Wolf 359. That's why they take ships out of drydock and have Enterprise bridge officers command several of the ships. Without the Borg, they'd be able to muster a larger fleet to stop the Romulans.