Guess on possible Secret Stretch

What is everyone's guess on what the last possible stretch could be ? I mean even if we made it with the extra 10k.

I have been hearing it might have been a another possible Wraith promo, but wouldn't that mean there put it to 4 wraiths. So I am guessing its most likely a Villian promo.

Or maybe America's Last Legacy :)

With only 3 defined Wraiths, we still have another 362 more to see.

And, America's Final Legacy sounds better than America's Last Legacy.