Does anyone know if Quicken plans to add the feature to also select which accounts for budget

I think they have indicated this will be coming at some point in the future, but we don't know when. There are a number of major budget features users have asked for, so I'd expect to see some significant changes to budgets in the future; it's likely a big project to re-write a large part of the budget portion of the program, which is why it's impossible to even guess at a timeframe, or which budget enhancements will come first.