With the ATAGS program, a lot of the electronics is being developed inhouse. Same with the Dhanush program, which is an upgrade over the original bofors with regards to all systems and not just the barrel length.
Also Tata SED are supposed to have developed all the electronics for the mounted gun system that they developed, using the Denel gun.
IA is happy with the performance of Dhanush-45 and is also happy with the Sharang program. The cost of the Sharang is very low and the numbers can be added. Now the assembly of the Sharang guns is being carried out at Vehicles Factory Jabalpur, while GCF and OFB Kanpur, work on the barrel for the Sharang and other parts and the Dhanush gun. This is something that I have suggested number of times on this forum in the past. Vehicles factory Jabalpur to be taken over by GCF and converted for manufacturing guns, rather than do screw driver assembly of Stallion trucks.
Currently we have the following guns or prototypes available in India.
1). Dhanush-45 In Production. Order is for only 114 guns, from the earlier projected 414 guns. The order and the production rate can be increased, if required.
2). Dhanush-52 gun, prototype is ready. Testing of the same has not been carried out. I don't know if OFB has carried out internal testing of the same.
3). Truck Mounted Dhanush gun. Prototype ready with Dhanush-52 gun.
4). Sharang project. In production. Order for 300 placed. Further order for another 300 guns is possible. This will complement the 180 Soltam upgrade of the M46 guns, carried out in the past.
5). Tata-Denel truck mounted 52 calibre gun. Prototype ready. Not tested by IA. Denel gun can be replaced with Dhanush or ATAGS gun, if required.
6). Bharat Forge, Bharat-52 gun. Prototype is ready since a long time. Gun tested by BF abroad. Testing by IA not carried out. Manufacturing capacity exists as BF has bought over and imported the entire factory setup from Austria. The production capacity can be increased or brought online, if orders are given. Baba Kalyani is on record saying that they can produced upto 200 guns per annum if required and if requisite orders are placed.
7). Ultra light 39 calibre gun prototype ready from BF. No testing by IA as yet. Don't know if BF has had the gun tested themselves or not.

Apart from the above, current inventory of the B77 bofors, can be easily upgraded to the Dhanush-45 or Dhanush-52 standard as and when required. Once the Dhanush and Sharang guns start entering service in numbers, batches of old Bofors guns can be sent for the upgrade.
If numbers are required in a hurry, carry out testing of the Bharat-52 gun from BF and if the same are OK, place an order for between 200-400 guns. BF can produce the same over 3 years, from the time of placement of the order. Place the order for the 300 balance Dhanush guns, as per original plan and have the OFB increase production to minimum 6 guns per month.
Athos or Nexter or any other gun, does not bring anything to the table, that we don't seem to already have. Committing to purchase 1580 guns, means more than half of all towed guns. In fact even more than that. Out the 3,000 155mm guns required, about 800 are supposed to be truck mounted versions. 100 tracked SPH. That leaves about 2,000-2,100 155mm towed guns. About 300 original bofors are already in service, plus 180 Soltam guns.
All of this does not even take into consideration the number of Pinaka regiments being added. Sadly as was reported sometime back, the number of projected Pinaka regiments seem to have been scaled back from 22 regiments to maybe 12 regiments. However, even 12 regiments of Pinaka (MK1 and MK2 combined), along with 2 regiments of Smerch and the 5 regiments of upgraded Grad regiments, will represent a massive upgrade in firepower for IA.