You forgot just one teeny tiny thingy - it's illegal to park ICE car on EV charging spot on the streets, in garages etc. So if the number of EVs grow the number of EV spots would grow which would take more space, not less.

If you take existing parking and make some of it EV charging, it doesn't take up much extra space; the charging equipment does take some space, of course, but sometimes there's room to be found for that.

Depending on EV adoption and how much charging people want/need, you can start with a couple spots that are active charging only, and see what that looks like. If the chargers are always full, consider adding more and/or having several spots for each charger and standards and practices to move your car and the charging plug when yours is full, etc. If the chargers are underused, consider making the spot open when the lot is full, etc.

If the number of EVs grows, ICE will shrink by as much so we can just convert regular parking spots to EV charging spots.