No, Williams got a 6 month un-paid leave of absence - aka "Suspension". (Like it really matters to him) he's friggin' loaded anyway. He'll be back in late June or early July with a mea culpa statement and things will resume like he never left ...
But, yea. Lester is doing a great job in the meantime.
As far as Jermey C. well ... who knows? He may be an asshat but he's a damn funny one who I really enjoy watching on Top Gear and I'd hate to see the show go on or die without him.
I think if BBC does fire Clarkson Top Gear should either end or completely change format again(maybe akin to the serious top gear of the 80s/90s), which I suspect won't be nearly as successful. I don't think the Comedy would work without Jeremy, that format was pretty much built around him. Richard and James, as much as I like them too, really need an obnoxious counter like Clarkson to balance their boring or irritatingly enthusiastic personalities. They're all legitimate Car guys but their personalities are so different that there's a tension and diversity that makes the show so watchable. Ultimately, maybe I'm just being a pessimist, I can't think of another personality that could take his place, whoever it would be would surely be a company man and that is tried and true creative poison.