Just realized I hardly addressed the OP, go me XD..

what's everyone think will be announced?
Future FFXIV content, including some portion of expansion information. From the trailer (probably?) we'll get hints of setting and jobs but if there is more than one job it'll not be both jobs then (saving some info for later), wonder if there will be any alien/space like visuals. Less likely but kind of hoping for a special FFXVI content drop as well.

any chances it will have expansion/job details since by now we should have had at least 1 fan fest and are behind on details only 1 patch left for the expansion and we have had no details on 6.0 at all.
I think it's likely some portion of the job details would be revealed, likely not being guaranteed... Either through strong hints in the trailer or just blatantly "oh btw" after the media completes. If there are two jobs I feel one will be kept a secret, if there is going to be two jobs and a limited job then it might be one job hint and limited job details.

anything anyone specifically wants to hear about?
Design philosophy and goals for the expansion, marrying content reveals with inspiration and desires, as well as the general future for the game, hopefully with a passion and voracious apatite to keep FFXIV (and SE in general) on that ivory hill. Like I'm not saying "next expansion if it doesn't do X then it's going to suck", that'd be silly, but say for example WoW has consistently improved old systems as they move forward and FFXIV is getting to that age where /if/ the game is going to continue to be their flagship it would be nice to see a sign of that idea that they are going to polish and re-kit it then when needed (as an example their glamour log, in comparison to most other major mmos, is pretty bad - to be fair it is totally functional, it does most of the job it needs but it's just like... would you rather drive the beat up car or the brand new fancy luxury vehicle? lol). However if they intend to make a new mmo after FFXIV's main saga concludes I'm not expecting them to rekit FFXIV too much- but I definitely would like to 'feel' an excitement for the future of their game(s). This may be difficult given covid and crunch together. . . but just thinking to myself it would be nice to feel that child like wonder and excitement.

Not feeling the need to over promise or lie, just being excited to talk about what they actually have (don't Cyperpunk me lol).

These feelings carry onto their next announcement too not just this one (if they weren't excited here it's not like I'd be "well RIP SE" lol).

More tangible points, besides major features that demonstrate an effort to push the envelope past whatever was already clearly readily possible I also really enjoy environments. For me it was fun to hear and see them talk about how they attempted to push the verticality of their zones as much as their engine could handle without exploding all over the place, I was pleased that they worked hard on that and I feel it was worth it (and hope they continue with like thoughts). Naturally jobs can be really fun, but say if it was a limited job JUST like BLU or Chemist I might be more ambivalent (or sad depending on the limited job), so jobs are not a guaranteed massive hype to me (although they totally can be). I make a note "just like BLU" since there might be different interpretations of the system that I might think are interesting, just not BLU (this isn't a blue thread so stripping down many reasons into one shallow point would simply be "I've no value in PF exclusive designed content", but that is a massive simplifications of a multi-point reason on why I'm not a fan /that/ interpretation). For example of they made a transforming based normal job I'd probably have an internal trainwreck of excitement, massive hype. Or if it was a limited job designed /actually/ for solo play (PF may be allowed but it at no point was part of the design consideration), maybe interesting. But if it was like "yo more BLU but now it's this transforming gimmicking that we couldn't think of creatively working in a normal situation even though many other mmos figured it out" I'd probably be very very disappointed. Which all to say is of course I want to hear about the jobs but my response to what I hear may vary, meanwhile I'm near 100% confident that whatever the environment is revealed I'll be excited.