How to convert to the new framework?

That was the intent
Evolve and mingle code as needed

I would bet 5+ years after the entire desktop framework has an equivalent. If memory serves from the 2014 XDC conference it was iOS, then console, then web, then desktop. AFAIK, iOS is still the only one that has everything in the new framework.

BTW, at a high level the Migrating to the New Xojo Framework page on the Dev Center might be helpful for some.

Nothing wrong in that. But if you go through posts in this forum, you will notice indeed the new framework is still a bit green, often underperforming as compared to the older one, sometimes way slower, or not having the features of the classic one.

In terms of processes, you must validate a production tool before jumping into a new process, with all that entails. Especially for a huge amount of existing code, it would seem foolish to jump on the new framework without thorough benchmarks of the new classes and methods. Pass the theoretical, I do not think anyone of us can give you a universal path to upgrade. It looks as a case by case basis, one class after the other, one method after the other.

You probably need to start evaluations, and decide on actual performances. As said above, you have years to plan a smooth transition. After all, OOP should make it easy to repaint room after room, instead of rebuilding the entire hotel…