I think at this stage South Africa is looking ahead in the race, as the domestic season is about to end.There is no international matches after 17th april in the country. The problem with the England Cricket Board is that the county season is starting in the country from april 9 (MCC VS. Durham). So its difficult for ECB to change the schedule. The other problem is that ECB will be under pressure even if they want to change the schedule of the county season because of their commitments with SKY Sports. So at this time South Africa is looking ahead in the race.
I also think that as the tournament wont be played in india Pakistani cricketers might play in IPL 2.