There is a lot of practical knowledge we can draw from electric cars, the weight of a Tesla S is similar to an M5, performance is similar, range is probably less with electric but not much. The main downside is the time taken to refuel, around 1 hour if you have a 120 amp supply, cost per mile is much less because no fuel tax.
Because engine weight offsets battery weight a practical electric trainer with a decent range looks feasible, longer range the battery weight overhauls the performance. Others have proposed 5x energy efficiency gains, we have not seen this in cars, maybe improved batteries would change the power weight balance.
The next question, is there a manufacturer willing to develope, certify and build such an aircraft that will probably sell at a few dozen each year.