When Lexus went fully Hybrid back in 2010/11 ( i think) they fully anticipated the tax changes. It was a bold move. The Germans came out with next Gen diesels beyind the ones that Toyota/Lexus had n the last 2000s. And then into 2014/15 came the whole dieselgate. What does this say about Toyota/Lexus marketing at that time ? I think very slow, crazy minimlistic advertesements , did not emphasise the benefits of Hybrid , it wasnlt just about fuel economy , it ws about smooth refined driving effortless, without the coursness of deisels. They didn;t even pish into business/fleet much ( though i think this was deliberate for this msrket). Then as you say they di not from 2015 quickly bring put PHEVs. And we know they can from the Toyota PHEV that came out last year. ( again Lexus slow with ts own as the rumoured 450+ not even out yet) . Much too slow.. Other brands quckly have cpme out with hybrids last few years, whilst they had been still selling diesels continuosly since when lexus had already stopped selling diesels, and have also moved onto PHEVs, ad EVs too. Lexus UK/EU did not emphasise their early changes and stance, and did not follow through with products quuckly enough. They still don't, still have "self charging" at its core!
I agree that about the direct4 in the ES, but my idea about the return of IS at some point in the future, will be with a cpmpetieve EV ( or fuel cell) as there needs to be an IS sized saloon. I know the market for saloons is dimishing but there is still a market hence why BMW, Merc, Audi, Vauxhall. Peugeot, volvo. The low sales numbers for IS were of its own making, and it is very contradcitory for the reason given for discontinouing the CT as i beleive was quite a good seling car.