They're never gonna change Elise with the aim of making her build more tanky, they've said that they think it's healthier for her to have to buy AP if she wants to make use of her early game leads. Elise is a lot easier to balance now than she was when she was built full tank (the difference in power between her solo queue and pro play performance is so much smaller now than it used to be) and my personal guess is that the majority of players would prefer to build her with some damage than build her full tank. I have ran into Elise players like yourself who preferred her old tank build but what I see from most players (including myself a lot of times) is actually building a fair bit more AP on her than is probably actually ideal. Elise has the kit of an assassin/diver and people generally want to actually make use of that rather than be the defensive peel tank that the Cocoon bot of old was.
I'd be interested to hear why you want full tank Elise back, because I've never really seen much reasoning for wanting that beyond (legitimately) "I miss being a stun bot", and I've always found that hard to understand because current Elise can still be a very defensive champion in the late game, she just has more uses beyond that now. It always feels like people just want their other abilities to be unsatisfying for no real reason, and that's especially strange to me because honestly I feel more effective at peeling for my backline as AP Elise a lot of the time (AP bruiser Elise is exceptional at killing tanks, so being able to stun AND melt the tanks threatening my carries feels very strong).
I really am genuinely very curious as to what is is you miss about tank Elise, the reason I'm being so negative about it is just because I have never understood why people would want it back. To me tank Elise fell off like a brick and only had one ability, while AP Elise stays relevant-ish late, can do what tank Elise did late while also having other roles and makes significantly better use of her overall kit. What is it I'm missing?