I absolutely assume this to be the case, but let's wait for an official word on this.
But seeing as 3.8 will continue to stick around, today's news doesn't really change much at all. I'd even say the only change is that now Frontier are "brave" enough to use 4.0 for future (story-)content.
The player base will still be split since apparently a sizeable group still prefers 3.8's rendering and planetary generation system. Or struggle with 4.0's performance.
Frontier will still have to kind of maintain two code bases.