[Kojak]

You don't know whether LNN (or some other take on LNN in an alternative reality) would have happened with Thames had they kept the franchise.

Indeed. I'm sure LWT even mentioned plans for a joint 7-day London news in their franchise submission in '91, so it had clearly been thought of for a while. I think even if Thames had won the franchise, they and LWT would have still eventually joined forces for at least the news.

(As an aside, am I right in thinking Frank Bough was initially considered to host London Tonight? ISTR he was and then he was hit by some scandal or other. I could just be imagining this, of course!)

Neil Buchanan bought Art Attack from TVS and ultimately made it through his own company for the next 15 years or so, it ultimately lasting longer than TVS itself did by some considerable margin. Some other TVS shows survived as well.

He did, and there ended up being multiple foreign-language adaptations of Art Attack (all filmed at Maidstone!) before he ultimately went and sold the whole format to Disney. Can't imagine that having happened if TVS had kept their franchise.