Well, they could be a bit busy with Res 8, especially if they are upgrading their engine with next gen tech for Res 8. So I wouldn't be surprised if they at least contracted out part of the work on Res 3 Remake to a 3rd party studio.
Partially may be fine. But the reason I think Capcom wouldn't outsource it fully is because after a downward spiral at the start of the generation, Capcom have been managed a lot better in recent years, and now they're as good as they've ever been again.
So I think management is extra careful now to not go back to their old mistakes, which was not giving their franchises the care and time they needed. And the former is always a known risk when using a different developer. Metroid Prime 4 is a recent example that comes to mind.
They also shifted management for Street Fighter earlier this year, and it's now the head of Monster Hunter in charge there, and not Yoshinori Ono.
So hopefully they won't take any major risks with their big titles. The RE spinoff is somewhat understandable, but I wouldn't gamble with RE3. Especially after how well received RE2 was, and the expectations ppl will have of its sequel.
According to one of the Resetera mods with insider info, he clarified today that it is being developed in-house for two years and a half already, just not by the same RE2 team. The same engine as RE7 and RE2 remake as expected, too.
That timeframe would explain why we're already seeing the cover art on PSN. Indicating a 2020 release.
But that would be interesting, considering that means RE3 was greenlit before they even showed the RE2 trailer at E3.
And Capcom said that RE2 sold "above expectations". So they didn't even expect it to do as well as it did, but they still started development on RE3?
That would also be before MHW became a huge success. So Capcom had only just started making a comeback with RE7.