It would be great to see Nadal in Perth. The organizers started making a list of players they wanted back in June. Sharapova and Nadal were at the top of the list. Obviously, the Sharapova idea was dropped when she committed to Gold Coast. Sharapova was being enlisted to play this year but Myskina, as the top Russian woman at the time, thwarted that plan when she accepted her first priority invitation.
It would be interesting to watch Nadal play mixed doubles. If they can get Medina Garrigues to partner him, it should be exciting. She's improved a lot as a doubles player and he has given doubles a good crack, having played with Tommy Robredo and Feliciano Lopez, most notably, in Davis Cup. I would expect them to be seeded second behind a Russian team.
Due to them pursuing Sharapova, the quest was also on to secure the services of Safin. He was approached first, apparently, from what I read in the paper. He has loved playing in Perth the last couple of years and he'd be a fool to change his routine after successive Australian Open final appearances. Since Sharapova declined the invitation, I'd expect the organizers to ask Myskina again. Although she and Safin haven't teamed well together in mixed doubles, she's the only one I can picture saying yes to an invitation. She's a bigger star than Dementieva and Petrova in Russia, and especially in Perth. She also loves playing for Russia.
Slovaks, Aussies, Russians, Germans, Spaniards, Serbians and maybe Argentines. If any of those speculations come true, then it's shaping up to be a good Hopman Cup.