It'll happen, I'm sure
No worries. Safebooru is currently purging so much crossover material that most of those will go bye-bye anyways. If that still doesn't happen, there can be a job made of it and it'll get done.
To boost your confidence, let me tell you that we've covered two hundred eighty three pages of 'cleavage' alone and going strong. We've got a lot of other tags we look into too. It'll get done.