Yeah, this has definitely been the plan for rebuilding franchise mode from the very foundation. SDS has repeatedly mentioned the 'old code' that franchise relies on. It's why any improvements to franchise mode year over year are pretty small. They're not going to dump a bunch of resources into the old franchise during each yearly game dev cycle.
As far as MTO, they developed the foundation and framework several years ago. It was pretty barebones during it's first release, but each year since, they've continued building it out. It's been a slow process for sure, and they haven't really wanted to admit that it will be the new franchise mode, but I'e been 100 percent certain over the past 2 years that this is their plan exactly.
Then, when MTO is built out to a point where it can do the things that franchise mode can do in it's current state (or possibly more) the old franchise mode will disappear forever. It's a solid plan when you understand the limited dev cycle for these yearly sports games. If SDS had been working on MTO out of public view over the time they've been developing it, we'd only have seen the small old franchise improvements year over year, and everyone would be 1000x more frustrated about the state of it.
I'm also really hoping that SDS can harness the better power (CPU) of the next-gen consoles to bring in some really, really deep simulation/stat tracking/trade and AI logic that wouldn't have been possible on older consoles. They can advertise MTO as the SMART franchise mode or whatever they want to call it, if players can really see how deep the mode is.
Wow, this post turned out quite longer than expected, but I'm just getting real excited as I think about possible improvements for MLBTS23 and the next few releases after that on next-gen.