Well, as it turned out the 2021+ PU remains identical. Is there a thread yet for the motors after this? (well, speculation thread I guess)
Though thoroughly unspecified some of the manufacturers want to bring its deployment forward by a year.
![Smile :)](./images/smilies/icon_e_smile.gif)
The realist in me says it will be a rather similar hybrids with some synthetic fuel gimmick*. Though not sure how. They keep whining how expensive it is, but at this point with know-how built up and the designs rather mature, I see no point in throwing out neither K or H. So what would change? More storage and electric power? Rather boring. synthetic or bio-fuels wont add anything technology wise, it's just fuel, they'll keep tuning it and the engine to work best together as always.
I'd prefer F1 to be forward thinking, innovative and cutting edge. I'd go with Ross Brawn's suggestion and go electric. Add some bleeding edge fuel cell system (probably don't allow teams developing their own and leave it big/relevant industrial firms ) a power limiter on the battery/fuel-cell output to promote efficiency and development: better efficency would mean more power and less weight.
*gimmick because I can't see them being used in the real world.