You are right on that, but I am sure if the seasons resume we will see some tight schedules with games almost every three days. Honestly I doubt the national leagues will care much about if the players are fit or not. If there is a certain timeframe in which the season could be finished the games will be played. But you are right, it will take some more weeks until we can think about resuming the leagues.
It has been a month since they enforce lockdown to each country, I'm sure after they resume those matches again the players will not play like their usual skills or maybe they let the bench player play first then they will play in another day. Most of those players might gain weight at some point because some of them don't have a personal gym in their homes. Most likely we will see a different play on most of the players but after sometimes they will return back to normal.