I think the two teams will probably continue, but I also think it will be less of a problem. My guess is that one of the teams was the dev team brought in during the acquisition of Slightly Mad Studios in 2019. While their certainly capable of programming a racing game, I imagine they found things a bit difficult having never worked with the EGO engine before, which is why some of the games seemed a bit off.
Presumably since both teams will be contributing to the overhaul everyone will get on the same page about how the engine works and how they want to structure their code to make things easier to hand off from year to year.
We will see what happens
