They could just insert the new toys by replacing the old ones as the result of some story. In other words, Classics Optimus would replace G1 Optimus. They couldn't do that with Alternators because of licensing, but there's nothing stopping them with Classics. I wouldn't mind if they even took a few liberties and removed Megatron's "wings" and Astrotrain's bullet-halves on the shuttle, for example. Some might wonder what the point is. I think it would be a good step towards legitimizing them as a real G1 update, and not some alternate universe crap. It would also be refreshing for the comic imo.