I'm sure you're right about gentrification in the BX, and you're also right that it sucks, but it is sort of inevitable. But it's not going to happen this year, or even next year.
Basically, although there are plenty of beautiful, spacious apartments in post-war buildings and cheap rents, I wouldn't recommend to England that he move there. For two reasons: because for what he wants to spend he can do better in terms of location, and because people there are (obviously) wary of people like him moving in, and he may not be welcomed with open arms.
and don't forget that he is moving in with his wife and safety is a real issue. while he may feel comfortable in a less safe area, his wife may not. this is a real issue, as anyone who has moved in with a significant other will tell you. you can't compromise comfort when it comes to where you live.