Of course there will be gameplay tweaks if there's a DLC (coming with a patch). But i'm not sure about it.
About what i know, i can't tells more but there will be new leagues.
I hope they will completely remove totally Liga Aguila because i prepared them for the next PLA league. For having a full South American experience in ML.
Would be easier to do than Uruguay, Peru or whatever from scratch, and there's 20 teams on it so it fits perfectly.
I already got a standalone Liga Aguila patch done for those who don't use our version of American teams (a lot lot of work and research) but also a Pesuniverse compatible version.But i can't share it now.
I didn't created promoted teams BTW, but there's more than 300 errors corrected (like in my thread from PES 2018), also no more "blank" faces as i've found every players, and 175 players created. They really needs more competent people for data...
I'm working for the +- final version (as there will be an NT errors/fake faces fix some weeks later some people will stay on PES 2020) and it's hell with our Others American teams to update, and some to replace (full Libertadores teams will be for PES 2021 : we're only 2 to work on it... Well for the moment one)
Seriously you're talking about Gameplay etc., but Data is part of if. Having plenty of players ambidextrous with the same height/weight, it's not representative. But Leagues/teams should share more informations, Konami isn't responsible.
And there's so much errors that i didn't even want to start an ML with this base.
Fortunately, someone close to Konami gives me a good new regarding data (well, not for lower league teams as they didn't worked on it)
Personnally, i made approximations with players comparison, like on this website:
https://www.foroalturas.com/f2-estatura-real-y-peso-real-de-futbolistas , and i think professionnally, that's what some websites should do. It's an hard work.
There's perhaps a program who can gives an approximations about an human height regarding pictures, but i never checked about it
If i was better for creating a website, i would like to work on something similar. Or purpose to Transfermarkt, soccerway, footballdatabase, Whoscored, as long as i'm paid for it. That's one of my speciality : checking an correcting errors. If someone got ideas or tips for me, it should transform a simple football website to something great. Of course, i couldn't do it alone (especially for some league, it's a bit hard to search in arabic or korean for example)