With this weight of opinion (leakage?) I don't see the need to put a question mark on the title.
Several reports indicate that Cricket Australia was not expecting the decision, though that Channel 9 has been, which is an interesting comment on the realities of contemporary cricket. As the ABC website puts it:
Channel Nine said cricket's leading wicket-taker would hold a press conference on Thursday to announce his career is over...Cricket Australia would neither confirm nor deny the reports but said it would be up to Warne and McGrath to make any announcements regarding their futures. "There is nothing we can say," said spokesman Peter Young.There is no doubt that Warne is - still is -a great bowler and that over his career he's been one of the greatest ever. If he's to wind down his career playing for Hampshire I wonder how much satisfaction (other than financial satisfaction) he'll get from that.
Nor do the Australian selectors seem to have a succession plan, if this report is accurate.