The problem is not keep the battery warm while parked, it's keeping the battery warm while driving. Most EVs can "preheat" themselves before you start in the morning, the smart one's might even learn the patterns and be ready when you get in at 07:30 every day.

The problem is that driving EVs in the cold costs a lot more energy. I've got a Ford Mustang Mach E for about 2.5 years now. In the winter the range that Ford claims drops by about 30 to 35%. That is a lot of range that goes missing just because the temp drops below 5 degrees Celsius.

Luckily I'm the perfect EV candidate: my daily commute is less than 50% of the total range so I can drive 2 days to the office if needed. And I can charge both at home and at the office.

The main problem that I see is that people cannot charge at home. If you are dependent on fast chargers by the side of the road you are going to have a hard time. The downtime for fast-chargers is enormous: my personal guess would be that they do not reach the 90% uptime. Which is bizar problem to have because a fast-charger and remote monitoring of the charger condition should be a solved problem by now.