Could the same boom happen going west, on the Atlantic? Ultimately a smaller market than going East, but here MAN does have one distinct advantage - you don't overfly any hubs between MAN and North America. Below Us Only Sea. Imagine.
I think MAN has all it's going to get going West to be honest. Add much more and something will give.
Potentially MAN-CLT with US as I doubt DUB-CLT will last given Ireland being a car crash economy right now and they're looking to use the paid for B767s to grow the network until more A332s arrive. CO / UA might see larger equipment on MAN-EWR with the second daily flight to another UA / CO hub. DL have both main hubs covered, AA still aren't year round daily on MAN-ORD and it's still a B757.
The main difference being that the US majors aren't government backed, vanity projects with bottomless money pits like Etihad. For a comparable European city of it's size, MAN has way more direct US traffic than one might expect. Also there is no dominant US carrier with the financial clout of say, Emirates.