No it won't. 4,000 for a premier league club is just window dressing, it is the first small stop to normality. The Premier League spunked over a billion pounds in the last transfer window and that is after 6 months of no one allowed in to watch. It will however stop clubs from league one down going out of business though.
Taking an educated guess I suspect it will be probably just the lower holte and lower and mid trinity that will be opened for two different viewing experiences with a best case 2,000 in each stand, provided Birmingham is in tier 1.