Second string CAS platforms like A10, reapers or spookies are employed only after gaining complete air superiority.
No, CAS fighters for example are used in early stages too, covered by Air superiority fighters and in Kosovo war for example, drones were used in early stages for recon roles, where fighters with recon pods were too vulnerable against air defences and even if 1 or 2 drone were shot down, it didn't bother much, since no pilot was lost and the cost was reasonable. Today with armed drones this will be even more the case, as I already told you, IAF has procured numbers of Israeli suicide drones for pre-emtive strikes, with armed Heron or Rustom H, difficult SEAD or CAS roles would be done in early stages as well, instead of risking a fighter, or a helicopter.
You can also take Kargil as an example, where partial air superiority was achieved and in this area armed drones or C130s would have been much more effective than the fast Mig 27s, or even an LCA.
Of course there won't be total air superiority in our cases, but that only increases the reasons to use drones / or weapons instead of fighters and where superiority is achieved, drones will have the explained operational and cost advantages over LCA.
You can also read this article about the RAF Reaper drones in comparison to Tornados, which even are dedicated strike fighters and still the advantage of drones gets evident:
UK's Reaper flying hunter-killer fleet 'to double' ? The Register
Correction, my contention is LCA will be able to carry out CAS along with CAP
Not possible with the MK1s and maybe not even for the MK2 (although that depends on the increased fuel capacity), since all hardpoints are occupied and no BVR missiles can be carrier in strike config. So any LCA in CAS role, requires another LCA in escort role to cover it, which makes it more useful to use LCA for CAP only, while drones are used for CAS. That's why I said that they will remain useful in interception roles, but will loose major parts of CAS to drones.
Again take Kargil as an example:
A typical bombing mission would involve 4 Mirages from 7 Squadron loaded with dumb bombs leaving a base in Punjab together with a two seat Mirage loaded with a LGB and Laser Designating pod. This 5 ship would rendezvous with 3 aircraft of 1 Squadron carrying Beyond Visual Range Weapons (Super 530D), operating out of another base. This rendezvous point would change on a mission to mission basis and once joined up, one escort aircraft would return. Once over Jammu and Kashmir they would be joined by Mig29s giving top cover.
Source: The Mirage 2000 in Kargil BR
8 Mirage and some Mig 29 for a CAS mission back than and also consider the time that they needed to recon the right targets and plan the mission before the strikes.
Today with modern fighters and armed drones, you would use half the numbers of fighters, since upgraded M2K-5s for example could used a strike load and still carry a useful number of AAMs, while drones offer live recon and even weapon guidance for the LGBs and if they are armed, they can even take out the targets on their own. All this, while the Migs still would provide top cover / CAP.
Even for worst case scenario for LCA, Say if not a single Mk2/mk1 is ever deployed in any role in western theatre, atleast 16 sqdns should fly around the clock CAP's at the eastern border. or would you like even that to be handled by rafales and Pmf/Fgfa's?
They will handle it anyway, since they remain to be the main air superiority fighters, but interceptions and CAP on the eastern front of course will be done by Mig 29s and LCAs. I also expect MK2s to be available at the eastern front too, since IAF will surely maintain their combo tactics with MKI and a fighter with low RCS.
However, the most capable fighters will always get preference and for the 2nd they when cost-effectivity comes in to the game, in CAS drones are the better choice in all accounts.