Welcome to FT. Given that Delta is still flying the route they will not book you on another airline (for direct flights). You can ask but I doubt it. You might be able to get a flight via one of their partners. But you should figure out the routing before calling.

If that fails, as the change more than 8 hours Delta will refund your miles without penalty and send you off to another airline.

So at this point I would start looking for another routing and/or airline that meets your schedule.