I despise bullying and as that's what's been reported then that's the reason he goes. I can't imagine a lesser ranked employee thumping Clarkson remaining in post. If May and Hammond are showing solidarity with a bully then they can walk too.
Anyways, the presentation style has been milked to death by the incumbent three. The best things about TG are the photography and the locations the cars are set in and, correct me if I'm wrong, that makes the production team more important than the presenters - not reflected in salaries and treatment I'll wager.