The Big East member schools just don't have any interest in any more programs right now because of the harmony of the double-bye situation as well as the success of the league. The Big East is going to get 5 or 6 this year, bringing the total to 20 or 21 of 40 possible in the four years of the league. It has been one of the Top 3 leagues in college basketball in its current history -- hard to argue it 'needs' to do anything.
There just is no catalyst. When the current 10-year media deal ends, I suppose its possible if the media partner (probably Fox again) wishes to broach the topic, it'll be discussed. But it's hard to find one new program, much less two, that moves the revenue needle for Fox. Hell, purely from a market perceptive in the footprint,
SLU and Duquense probably make the most sense. But given they are both abysmal programs, they aren't getting an invite.