I do not agree that banning new ICE cars will slow development of EV's. I do foresee a few speed bumps however.

Some things that I do foresee would be older cars being kept on the road longer, 3rd party parts sites making more money, tow trucks making more money and often being unavailable for hours on end, independent mechanics will likely be spread thin leading to more cars sitting driveways with the legal non-op status and conversely auto-dealer mechanics may see less cars as everything would eventually move out of warranty and require service from the independent mechanics that would already be spread thin. The dealer and non-dealer mechanics will all need to retrain for EV's and it's not as simple as some may think.

Another factor I see is that the augmentation of the existing power grid will need to accelerate dramatically and that may have affects on inflation. Distributed battery storage will have to accelerate dramatically. Hopefully sooner than later we move away from current battery tech and move to sodium like China did, otherwise I foresee material supply and logistic issues not to mention the dependence on China and Africa for a limited supply of the current materials. There need to be massive tax incentives for solar, battery, inverters, level II home EV chargers, etc...

Another potential issue is weight. EV cars only weigh about 1K pounds more than their equivalent ICE but this number goes up a bit as the vehicle gets bigger and there will always be a need for bigger vehicles. The EV tech has not shown itself to be ready for consumer towing vehicles such as Ford F350-650, Chevy 3500-6500 and some ICE setups are already pushing weight limits. People will have to tow less product and for less distance which is a non-starter for some. Those will be the ICE vehicles that remain on the road for some time. Battery tech will need to improve leading to smaller and lighter batteries. Perhaps solid state 3D printed? The Sheriff, search and rescue will need EV's that can haul UTV's and snowmobiles into the mountains to rescue people. Livestock are moved by diesel trucks. AFAIK there are no EV's that would meet these hard requirements as of yet. That extra weight will also contribute to more brake dust and more people sliding off icy and slushy roads.

Finally the elephant in the room is the lack of chargers. Both the electrical infrastructure and acquisition of 145k+ charging stations needs to happen by 2032. This may also have implications on inflation. Why 145K? I didn't just make that up. There are 145K gas stations in the US that need to replace all of their pumps with level III chargers. Anything less will result in people sitting in parking lots for hours and having massive lines. It does not even have to be gas stations. It could be Walmart, Walgreens, CVS, the grocery store, a re-purposed parking lot, etc... Currently about 6% of the vehicle sales in the US are EV's but that does not mean they no longer have an ICE car. When that reaches some critical mass everyone will have to charge at home or be stuck sitting in lines at charging stations. People will not tolerate that limitation and word will quickly get around thus limiting sales of new EV's and some EV's may end up sitting in a garage. There are many people that will not have the option of charging at home.