So you can be more specific in what you think is so unproven and undeveloped- nothing being advocated is actually a secret.
The CARB EV mandate and LEVIII are the ones driving things in the US going forward, so while it's cool to blame the former President for you, it's pretty inaccurate.
For the EV mandate, BEV's have been around for a long time, there are tweaks going on for the motor to make it more efficient, but I would not call that unproven or undeveloped- that's massively developed. Batteries is where the real game is for EV's And as far as I'm concerned, it's not moving nearly fast enough- as we are generally using the same Lithium based chemistry that we've been using for the last decade. There are tweaks available to it, but the required quantum change seems to be still far away. Since Hybrids are also part of the EV mandate- plug in hybrids and normal hybrids have been around for many years now- HEV's for 2 decades. The reason those are still important is the cost of an entire powertrain plus a large generator is still cheaper than the range extending battery packs. As far as I'm concerned, the only real "new" aspect to hybrids are mild hybrids- which replaces the alternator with a motor-generator and a small battery to supply some mild hybrid energy recovery. And of that, the real question is the cost of the battery, since MHEV's are supposed to be really inexpensive. But of the EV mandate, a gross majority of those will have ICE's powering them.
I worked many years on the LEVIII coming up, and while it mandates that the fleet average is going to be SULEV30, the path to get there may not be easy, but I saw it as very likely. Nothing required in LEVIII is new or even unproven, it's just development. To give the people some perspective, in 2025, the entire fleet of new cars and light trucks will be as clean as the cleanest version of cars that are available right now. And that's considerably lower than the fleet average 20 years ago.
There are some new ideas for ICE's coming, but they are pretty much all tweaks from the DI change that happened around 2010.
So I'm really not sure what you mean by unproven and undeveloped.
Is there a massive risk to be an ICE engineer going forward? Sure, I knew quite a few fellow engineers that were forced to retire when I did. But it's not the end of ICE's, it was more a purge of people who had qualified for retirement and they wanted to get them off the books.
Are BEV's perfect? Not even close. I have some serious questions that most BEV's advocates don't want to address. But that hardly means they are unproven and undeveloped.