@Oscar @Horus
Knowing that the PAA has 30 T129Bs on order and, in all likelihood, it could potentially procure the ATAK-2 in 10 years (when available), do you think there's enough scope to go even lighter in terms of attack helicopters?
China and Japan have shown that even with a 4 to 4.5 ton (MTOW), tandem-seated design (e.g. Z-19E, OH-1) you can have an integrated EO/IR turret with SALH ATGM and 70 mm rockets. Sure, there are clear range and payload limits, but the cost of a "Cobra rehash" is markedly much less than a larger attack helicopter.
With the T129, the PAA has effectively handled its high-altitude operating ops environment, which had been a major strain on the AH-1F/S over the past decade. Given how fiscal limits will constrain the PAA's ability to pick-up many 8+ ton attack helicopter designs (or at least at a fast enough pace), perhaps a Z-19E/OH-1-like design has merits?
Such helicopters can operate in lower altitude CAS environments (deserts, plains), yet - qualitatively speaking - offer the core anti-tank and anti-infantry capability of the ATAK. But the downside is defensibility (not enough power for more armour, entirely reliant on the self-protection suite).
Likewise, while the procurement cost is certain to be lower, you'd need more of the small attack helicopter to match the impact of a larger counterpart. That could add to the long-term operating cost of having them, and - possibly - their impact could be matched by a fewer number of ATAK/ATAK-2.
Really, the question is ... would you have enough money to afford the necessary number of ATAK-2 or would you need to think about a cheaper/lighter platform as a means to spread CAS coverage across more of your force?
Still, the alternative is rational as well.
Just double-down on the platform you chose (T129) and, in turn, gradually build-up. You have a 30-40+ year life-cycle, so if you just issue incremental orders on an annual (or at least regular) basis of 4-6 per year in 10-15 years, you can add 40-60+ more ATAK/-2.
In fact, in contrast to the Heavy/Light combination India is taking via the AH-64E and LCH, the ATAK-2 would cut down the middle as a 8-ton AH-1Z-class system. Your approach with such a platform would be to consolidate on that one, medium-weight platform, but your final numbers would sit between India's Apache and LCH forces.