There's a lot of speculation that it is indeed a marketing plot and the model is just a step improvement over current capabilities... and the real reason they aren't releasing the model is they are compute constrained and cannot serve the model. To my knowledge there's no proof of this however, but given the fact that literally 60 days ago they made Mythos out to be the end of the world and last Friday they announced that they will release the model in a few weeks, I feel like it was indeed something along those lines (marketing ploy).