The way the rules are now, it's highly probably customer and manufacturer teams will run the same PU next year.
This is because the FIA plugged the hole in the rules; at this moment the tokens have to be spent before the season begins. This also means the homologation has to happen before the season, and the way the rules are constructed it'll mean previous specs are not regulatory to run.
There are 3 notes I have to make about this:
-There is a push behind the scenes for both in-season development and for previous performance specs to be allowed. However for that to happen at this moment now, all the teams have to agree. The likely-hood that atleast one customer team votes against being basically stuck with a previous perfomance spec PU, is quite high.
-The manufacturers of course retain the option to update the PU throughout the season for costs, safety, reliability. It's usually the latter, so let's call those reliability specs. This has an impact if the manufacturer builds in extra performance through the token updates before the season starts, but can't complete extract the extra performance inmediately and needs a reliability upgrade later in the season.
-Having the same PU is still not the same as having the same performance. Oil and fuel make a very, very important difference and the manufacturer still has the best collection of data. None of these things are forced to be shared with customer teams.