It all depends upon our requirements V/s better options available per finances and making the most out of every option for more & more better product. One can't go shopping in such scenarios without exhausting every option. There is a lot difference between Buying & inducting a new plane into inventory as compare to already existing setup let alone the experience at hand. If it has to go by every point under merit to select one of two available products at hand; in-fact every professional out there even non PAF will suggest to go for Vipers. Beside our experience with Viper platforms; much of setup already exists for maintenance etc. Furthermore, let's say that a new bird will in-fact take couple of years for almost full familiarization, tactics development etc. new platform does need a lot of time & energy as well for induction as compare to existing setup+experience and that too for Viper.
However, if you are going to ask about that Vipers aren't coming then in-fact, we are about to unveil Thunder Block-III which, as per our doctrine & tactics/needs; will serve the purpose in most areas that J-10 can offer atm.
