I am sure someone could build something similar (or even better) as the BitShares blockchain with behalf of EOS, but it simply isn't here yet and might take years for someone to actually make it. Why create something similar when its already here...ready to be integrated and supply their needs? I agree btw, Bitspark seems like the perfect fit and is likely to give a lot of traction to BitShares! (it's why I am stocking it up even more than BTS atm ^^).