Revelations from Patch 7.2: Seekers of Eternity

[Cleretic]

I don't think there's a set rule when they start leaving bread crumbs for the next expansion, but x.3 would be the earliest considering they introduced Fandaniel at the end of 5.3. Would not be surprised if we get a 'meanwhile elsewhere' cutscene at the end of 7.3 that seems out of place.

Well, no, they introduced Fandaniel in 5.1, we just didn't know who the hell he WAS until 5.3. And didn't even have the faintest idea what he was doing until 5.4. (And even then, a lot of people got that wrong.)

Iscah's right that x.4 is traditionally the 'setup for the next time' chapter. 3.4 introduced the Griffin and pointed us at Ala Mhigo, 4.4 introduced 'Solus Galvus'. At best, if you're really hoping to look more at the next expansion, 7.3 is going to tell you what character that already exists will be worth keeping an eye on. But even then, be aware of a false positive; the Warriors of Darkness were still lingering as of the end of 3.3.