> since Google showed you don't need to retrain an autoregressive model to rework it for diffusion inference

IIRC you do need to retrain the model, just closer to the level of finetuning rather than e.g. pretraining from scratch. Which also means that the model will perform differently with a different capability profile.

If that's true, that's the real answer, or more like anty-answer because you're saying basically: hey, nothing should stop them.