SU35 is indeed a formidable aircraft.however it doesn't come cheap. We are on our way to build our own 5th gen aircraft, the project Azm, which will be a gen ahead of SU35 and will do these deep strikes roles plus air superiority over enemy airspace.
I am all up for procuring s400, a real force multiplier and an area of defence which we desperately needs to plug the gaps. Su35 on other hand is 4.5 Gen aircraft and when we are well on our way to build our own 5th gen aircraft, it doesn't make sense to order su35 now which will be delivered few years down the line and by that time our own 5th gen jet will be in mid-final stages of development. If you know what I mean.