I don't know what's happened to the C350e successor. There was all sorts on the rumour mill wasn't there? You see loads about, and BMW immediately brought out a 330e in their new 3 series so they obviously see a market for it. It's a shame.
I think the BiK bands in the UK mean you can’t easily fit enough batteries in a legacy platform to hit a low tax rate for company car drivers. If you do, the only role of the engine is a range extender and again, that presents platform challenges.
Fleets buy a huge proportion of new cars but from what I hear, lots of people are abandoning company car schemes to take advantage of depressed used car prices (and engines that aren’t 1.4 litre fuel sippers).