To be fair I am amazed at how competent Kolarov looks at CB. His only redeeming features for us have been his ability to get forward and whip in a good cross, so I'm surprised he's looked ok there in pre-season and today. As you say, no chance he stays there though once everyone is fit, thank feck. Do not think Fernandinho will play there either with any regularity. A lot of people jumped onto the quote Pep made about him playing there, but he said it in response to a specific question about which of our midfielders could play CB, and tellingly he had to pause for a couple of seconds! He could do a job there for sure (did so in the derby last season for 30+ minutes) but he's too valuable in midfield to play there, plus we have better CBs in Otamendi, Kompany and Stones.
Hard to say until I see all the players settle in and how they adapt to Pep's ideas, but on paper, right now I'd say something like this:
Hart
Zabaleta Kompany Stones Clichy
Gundogan Fernandinho
Sterling de Bruyne Silva
Aguero
All depends on how Pep can fit Silva and de Bruyne into the same side to be honest.