You're surely entitled to your opinion but that doesn't mean you're right, just means you have an opinion just like the rest of us.
Just because you feel sponsorship based attractions don't last doesn't mean they won't or can't. For example CoP, not only did it last but has become a fixture in MK. The reason it didn't last in DL is because GE felt their money would be best spent at WDW where there would be more tourists, more return on their investment. So the whole attraction got moved in its entirety, again not because GE was unhappy with it or wanted to end their sponsorship, but rather because they actually wanted more people to see it. And even after GE ended their sponsorship, the attraction has continued to this day. Now its seen better days, and needs an update again. But overall its still is an example of how a sponsor can help create a stellar attraction that can stand the test of time. Which is my whole point.
You bought up another example of where a sponsor improved an existing attraction in Test Track with GMs sponsorship. Last I checked GM was still making cars. Even if they are closing some US operations they still plan to sell to the US market. So why would they end their sponsorship just because of closure of some US plants?
I'm the first to say IP based attraction can and do have their place in the parks, I've argued many times on this very site for their usage. But there is something to be said about the classic TL attractions that were created hand-in-hand with their respective sponsors. There is a reason why we're still talking about them today, because they are iconic and classic for a reason that goes beyond the sponsor. And I personally think the next generation TL needs the same thing. Now that's not to say an IP attraction can't have its place in the new TL, but I think just the right sponsorship can help create the next generations version of CoP or ATIS.