Honestly, yeah. Unless you really want to play Demon's Souls there isn't a lot of reason to get one. Wait until they make one with more storage and hopefully that isn't so ridiculously huge and nearly impossible to use horizontally. (slight edit: You do get some improvements even over a Pro but judging from your other posts I don't think they would be worth it to you personally)
I haven't watched much since they changed hosts, but yeah old school Top Gear and Doctor Who were shows I actually kept up with. I just couldn't be bothered to watch Prime Video on my computer which was the only option I really had until I bought the OLED or I would have watched The Grand Tour a long time ago.
Yes, for me personally, I'm not sure whether it will pay to move to a 5 until they're almost getting ready to put out a 6. And by then, Sony might have decided to start putting out all of its first-party stuff on PCs sooner than later, which would pretty much make getting a 5 utterly pointless to me.
No, my wife boycotted the show and virtually pretended it never existed after Clarkson was fired--but she loved The Grand Tour. You might want to check out some of the other Hammond and May shows that are on Prime too. There's some old stuff and James May has a show about wandering around and generally faffing about in Japan and a new one that's a cooking show, of all things.