Well, going by the name "Mid Life Upgrade", I'm assuming that the upgrades will extend the service life to as many years of service as has already been achieved. That is, it should extend the life of our F-16s to beyond the next decade, maybe even into the 2030s (we're very good at extracting every last bit of juice from our hardware, ex. Mirages, A-5s, F-7s).
After the MLU, our F-16s should be very close to the Block 52 standard, which means that for objective purposes, we can consider them F-16 Block 50s. Thus, the total number after the 18 new ones and 54 MLU minus 9 lost should be 63 F-16s Block 50/52. Let me tell you, that will give us great punching power against any Indian threat.