I don't think the Warriors would've allowed them to escape.
After all, Zeke and co. were waiting there because they knew the Coordinate would come to them, and that's the one thing they needed before going back home.
The only reason they had to let them go in the actual events of the manga, is because they were all overwhelmed; Zeke couldn't transform for a while, Bert couldn't be saved and Reiner almost died as well (plus all the Mindless Titans had been wiped).
But if none of that happened and all the Warriors were still good to go, I don't imagine them just letting Eren and the rest escape.
Plus with Zeke still being able to throw them boulders and whatnot, not to mention the circle of Mindless Titans that would surely run after them as well.
But let's say that they did let them retreat.
Zeke did say "you can worry about saving Annie later", so maybe they could've all gone towards the inner Walls looking for Eren but also Annie.
However, this wouldn't really be a clever plan at all.
It's one thing to fight in Shiganshina where they molded the terrain to their advantage, but going against the Walls + defenses + hundreds/thousands of soldiers at the same time, plus canon fire and whatnot... I think the Warriors would've lost most of their advantages.
Besides, they wouldn't really know where to look for Eren and Annie, since they could literally be anywhere, but when the SL came to Shiganshina it was a lot easier because Eren had to be in there somewhere, they just had to find him.
Another option is that they would've simply left Paradis and gone back to Marley.
Because they would still have Bert/the Colossal Titan, I think we can assume that there wouldn't have been a war fought between Marley and other countries.
Eventually, they would've gone back yet another time - this time with the Jaws as well - and I think they would've gotten the job properly done this time around.
With no war = no 3 year timeskip.
Even if the Scouting Legion had managed to reach the basement and whatnot, it's highly likely that the Warriors would've come back shortly after they left, and that wouldn't have given the Walldians enough time to do anything with their findings.
That's what comes to mind at the top off my head.
(and of course if we all take into account Levi + Hange's death we can pretty much be sure that they would be screwed for good, even with Erwin/Armin still around)
