I could be totally wrong, but based on what I have read...franchise mode is built on legacy code which is why it has lagged behind other modes like March to October and Diamond Dynasty. Modernizing that code would be a huge undertaking and require a lot of time and resources that simply won't be allocated to the developers. Rather than do that, what you'll probably see is them take March to October and use that as their means of providing a modern franchise mode.
It's a scary thing to think about because it could make franchise mode players feel alienated and give the indication that they're trying to phase franchise mode out of the game completely, or at the very least just continue to nickel and dime the mode from year to year adding just enough to keep us coming back.
I truly hope I'm wrong as franchise mode to me is the most pure and authentic way to play the game. You get to do all the things you see happening within the real world of MLB. I love baseball and I love MLB the Show. My hope is that they might build a new franchise mode from the ground up taking what they've done with MTO and using it to build a true modern franchise mode. I'd be more than willing to endure a full dev cycle without any additions to the legacy code to allow them the time to do it.
But who knows what they might do. Baseball is baseball and compared to other sports games MLB is far and away the best. EA is a trainwreck and I refuse to give them any of my money. The Show is what I look forward to every year.