*If* the rumor is correct, I'd actually worry about the immediate future of DW. We might be entering a time where they'd rest the series again. Wait until they find someone who is both suitable and interested. It sounds like that is difficult now--particularly with the constraints in place--regular series of 10 episodes.I'm sure it's all just hot air and gossip, but if Chibnall did leave that would make something of a mockery of how much effort the BBC put into getting him; allowing him to rest after Broadchurch, persuading Moffat to keep going etc.
If (big if) this is true then I hope the BBC has a backup plan in terms of a replacement who can slot in easily.
Ultimately, that's what killed the classic series back in '89--the lack of interest among producers in the BBC to produce DW.
But, I'm not willing to believe the rumor quite yet!