Since many people are confused about this, let me clarify it this way:
The T80UDs Pakistan has will all be upgraded with Parts from the Oplot. These aren’t just some upgrades, they’re literally partial rebuilds of our T80UDs.
This upgrade project started a few years ago now and it will take time. These will be upgraded slowly in batches. The first batch was of 88 tanks if I recall correctly, then there was another tender for the upgrade of 25 more, then we hear about this deal. All of these are for the same upgrade project, just more tanks being upgraded. So we can expect to see all the T80UDs we have to be upgraded with oplot parts by say 2025. This will extend their usefulness beyond 2035.
Looking at the rest of the Tank fleet we can put it this way;
VT-4s will keep arriving for a few years, 300 in the first batch, then more. The VT4s we get say 5 years later won’t necessarily be the same as the ones we’re getting now, they will continue to evolve too as a project, maybe even with local upgrades in the further future. These are essentially to quickly replace the really old tanks the PA still has.
AK-1 production will continue at full steam, and just as the Base model AKs produced in later years had upgrades over the Base model AKs produced in early years, AK-1 will continue to get upgrades as well over its production lifetime, until eventually a major upgrade is done and it becomes AK-2, and the cycle continues.
The base model AKs will likely not be upgraded, at least not anytime soon, but they don’t exactly need the upgrades yet.
Both of these will be the new tank acquisitions to replace older ones, VT4 had to be bought both for quicker replacements as AK project hit a few hiccups and for the technological advantage if India decides to buy T90MS in the future.
T80UDs will all be upgraded to oplots over the next few years and will remain in service along side the above mentioned two. It is a financially sound decision to upgrade these, Pakistan did want the Oplots but there are some glaring reliability and delivery issues with those, so why not upgrade our own T80s at a cheaper cost. These three will be the front line and are all very capable tanks.
Next are the 150 something Type 85s. They were supposed to be retired too but due to delays in the original procurement of VT4 they were all upgraded too. And as such they are still potent tanks and will serve for a few more years now as second line tanks.
Al-Zarrar will remain in service for quite a while too, with the rest of the Type 59 fleet being upgraded as well. The Al-Zarrar is Not a bad tank at all for our use, it won’t be fighting abrams or T-14 Armata. The thing to remember is that more than half the Indian fleet is also T72s, which are really no better than the Al-zarrar or the Type 85s. So to keep the numbers in balance, the huge amount of AL-zarrars we have are a perfect second line tank fleet. But they will not be upgraded further at all and will need to be replaced by the end of this decade, VT4, AK-1/AK-2 will be doing that.
Some Type 69s got basic upgrades and were given to FC, where they will see good use on the Pak-Afghan border, the remaining will be retired as VT4 and AK1s continue to come or will also be handed over to FC.
AZ and Type 85 can also be used on the western front if needed.
All remaining type 59s will either be upgraded to Al-Zarrar or will be replaced by VT4s and AK1s.
All in all by 2025 the PA is going to have a massive tank fleet of VT4, AK/AK-1 and Oplots as frontline tanks with AZs and Type 85s as second line tanks. And all 3000+ Are capable of night time combat.
This gives us not only the technological advantage, as India so far has no T90MS and the Arjun is a joke. But it also basically means the Indian numerical advantage is over, both when it comes to modern tanks and second line tanks. Especially since they have to dedicate resources to China. We also do not have to replace our tanks 1:1, if we have 3000 tanks right now and 1000 of them are obsolete, then replacing them with just 500 modern ones is still an upgrade in capability, not a downgrade. That’s why a 1:1 replacement is not needed.