Instead of a heavy tanks, perharps US can have a heavy in the role of supporting like the Jumbo Sherman, M12 GMC or Callie? That way US can remain competitive till late game without breaking their faction design.
Easy 8 fills that role for now as well as bulldozer.
I'd like to see Jumbo eventually, but it would be just another KV-1, so I won't cry if they won't implement it.