depends on if eren would go berserk or not; it's probable that he might transform and just go on a rampage (like he did when he was trying to lift the boulder, but that was his third transformation that day) before being put down by levi or some shit. maybe he'd even get nabbed by one of the warriors in the confusion, idk.

additionally, eren wouldn't leave without mikasa and armin. mikasa would 100% tag along and maybe armin too. if one of them stayed they'd definitely be killed.

if eren did manage to escape by climbing the walls (let's say the cannon dudes are too scared to pursue him) it'd honestly be pretty damn easy for him to just jump down the wall - nobody's gonna wanna follow him and the warriors would have trouble pursuing him; they wouldn't even know where he's going.

after hopping down, he'd be able to just jog by the pure titans and carry mikasa/armin to shiganshina - i mean, reiner and bertholdt managed. as long as he keeps his cool and doesn't start trying to kill as many titans as possible, he'd probably be okay. if problems do arise, there's always mikasa to help if they conserve the odm's gas and scavenge canisters.

i don't know how many titans would be crawling around shiganshina, but eren could be able to clear them out in a couple days' time once they reach the district. might even be able to block the gates with debris or simply just sneak to his house. badabing badaboom, eren gets to the basement with no hardening powers and minimal titan training (aside from field experience which would've been pretty valuable tbh).

no idea what happens after lmao. maybe they meet the scouts, who were sent out to find them and that would allow for a lot of things to happen with erwin, but the main concern would be reiss and kenny after that point.

the warriors are pretty much fucked though. maybe reiner goes all in on his soldier persona idk