Very bad analogy. A gun is good up to 4Km. A laser will probably give you a little more. But XRSAM etc are needed for long range engagement.
So, with current technology, a laser can replace a gun, not a missile.
Just imagine a Biho or Pantsir with missiles and a laser turret.
That's why I put our date as 2025-35, and the US before that.
No, it won't be difficult to develop 20 to 40mm cannons. But our stuff's gonna suck compared to imports, which is my point. That's also the reason why DRDO has not pursued it. It's not a good idea to develop everything with our level of funding when imports are much cheaper and better. There's a lot of stuff DRDO has not bothered with, like MANPADS that will go on mobile AD.
You can always develop your own mobile AD system with an imported gun and missile anyway, which is not really a very efficient way to go about it when the imports are a whole lot better. You will notice that the US will also be importing their mobile AD.
Most of the stuff you named will be inducted over the next 20 years will need imported cannons anyway.
Today India uses in 30 mm primarily 2A42, for all of the BMP variants, That's roughly 2000 units which are due to be replaced ( so potentially 2000 units of 30mm autocannon there) OFB makes this gun and badges names like medak and CRN91 which finds use on board IN/CG ships.
Su30's and Mig29's use the GSH 30 -1(including the ), Mil Mi24 uses GSH-30-2; All of Eurojets in IAF are the Aden family , Aden30/Defa 550/Giat 30; Then there is the 30mm auto for AH64 - M230; and finally every IN CIWS is around the AK630 using the GSH-6-30, And then we have the 20mm family that includes thee GSH-1-23, GSH-2-23, Nexter 20, and the Oerlikon 20mm systems on multiple aerial platforms and ships.
Roughly a force that can utilize close to anywhere between 3000 to 4000 high caliber gun systems. If I was a gun maker I would be looking at monopolizing every platform fielded in India with an Indian 20mm and 30mm variant. Heck i would even looking at developing 40mm and 76 mm system in-house to be fielded in every Naval ship.
This is a big market, with very few players out there where a low-cost main gun and low-cost CIWS solution would help driving India becoming a real player in naval shipbuilding where we can provide end to end solution to export cutomers. In my book, such systems which are achievable and realistic are a slam dunk.