>who are willing to actually spend that money
Money mean nothing. It is simply medium of exchange. The question is, is there anything to exchange? And the answer is yeas, and position of white collar workers doesn't affect availability of things for exchange. There's no reason for recession, there is nothing that can hinder ability of blue collar workers to create goods and services, all that things that when combined is called "wealth".
Don't think in the meaningless category of "what set of digits will be printed in the piece of paper called paycheck?". Think in the terms, that are implied: "What goods and services blue collar workers can't afford to themselves?". And it will become clear that the set of unaffordable goods and services to blue collar workers will decrease because of the replacement white collar workers with AI, because it is not hinder their ability to create those goods and services.