It's quite possible you can have an all-electric range-extender with over 1000 miles; there was some talk Tesla was looking into current-gen Aluminium-air batteries for that purpose; afaik Al-air is currently the most mature metal-air battery with some actual deployment in limited applications. Downside for conventional aluminium-air is they can't just be recharged once you use up the charge, but the Aluminium needs to be mechanically replaced after the charge has been used up.

Practicalities of that exact scheme sound dubious, but the concept is promising; early gen of some metal-air batteries, even if rechargable could be quite limited in the number of cycles it can last, so be a poor fit for being the main battery bank of an EV car. As a range extender though, this is much less limiting, so could find first use like that, in practice giving 1000 miles range for occasional long trips.