I hope Murray has reached his prime, so he can meet Nadal at AO 2013, so Nadal can lead the hard-court slam H2H 3-2 (and 2-1 at the Australian Open). That would give Nadal a 7-2 lead in slams.
It's going to come down to his performace at the WTF to see if he's truly hit his prime. Wins over Djokovic and Federer at WTF would really say something.
If you mean "prime" like now the tournies are opening up where Nadal doesn't play for a few months out of the year and misses a lot of big tournies and djokovic now gets knocked out, well then yes. Murray is one lucky *******. If fed had this when he was young, he would have dominated more than now.