http://uk.cricinfo.com/db/FORTHCOMING/YEARLY_CRICKET_CALENDAR.html
By that reckoning its:
Australia - 4
Bangladesh - 0
England - 11
India - 4
New Zealand - 2
Pakistan - 4
South Africa - 2
Sri Lanka - 3
West Indies - 4
Zimbabwe - 0 (obviously)
However there's also the following tours not scheduled:
SA in SL (presumably 2 Tests)
India in SL (presumably 2 Tests)
India in Bangladesh (presumably 2 Tests)
WI in Pakistan (3?)
India in SA (2 or 3, depending on when the cut off for the new year is)
Bangladesh in NZ (probably 2)
That makes Murali a good bet for this year - probably 7 more games is about 45-50 wickets if he stays fit, putting him at about the 70 mark.
To beat that, Ntini would need 41 in 6 or 7, Warne 42 in 4, Asif 45 in 7, Kumble 45 in 8 or Hoggard 57 in 11!