It's possible, but unlikely unless Viraat develops serious mechanical problems in the near future preventing her from continuing in service. Also, the Indians tend to procrastinate over these decisions for years (look at how long they took to close the deal on Gorshkov) so by the time a deal was struck the new Vikrant might be ready for sea! Having said that, I still think all of the Invincibles are destined for further careers probably in the Indian ocean and/or Pacific. Pakistan might try to build on it's new friendlier relations with the west (still a long way to go on that though) and buy Invincible as part of a package deal for F-35Bs just as India bought Mig29s with a carrier thrown in. Invincible is in good condition, well maintained, fitted with modern command and control facilities, good accomodation and a modern radar suite (she is far in advance of anything in the Pakistani Navy or the IN for that matter) so would represent a real step change in capability for either Navy. Without a carrier, the PN will always be an 'also ran' in any naval conflict in the Indian Ocean. Invincible won't officially be 'on the market' until 2010, and Illustrious and Ark Royal will be flying the white ensign for quite a while after that (at least 2014 and 2016 respectively, though I suspect Ark will be retained a while longer in the LPH role simply because it is cheaper to do so than buying a replacement in the short term).
