In your review of Survivor Series 1989, you noted that Tully Blanchard was pulled from the show and that his WWF career was over after a failed drug test.
However, they already had a Brainbusters vs Rockers SNME match in the can that they aired after Survivor Series. There was a pre-match promo with the Busters and Heenan teasing dissention, and during the match itself Heenan walked out on the team, presumably leaving them for good.
So what was the original plan going forward? Were they going to run with the Brainbusters as a face team, or were they being written out of the WWF anyway?
They were being written out anyway. Turner made no secret of wanting them back for the Horsemen revival and they had already given notice. So Vince decided to salt the earth on their way out with the bullshit drug test that no one else ever failed. And then Tully got lowballed by Jim Herd because of the failure and burned that bridge too.