Those jets will weigh more & consume more fuel, decreasing range.
Why would you assume that?
The turboprops are rather fuel efficient, but with large turbofans I think it would be interesting.
Needless to say the new fuel efficient jet engines replacing the engines on the An-124 should improve performance and be more fuel efficient... that should go without saying because engines from that period are not super fuel efficient so a modern high tech fuel efficient model should both increase thrust and reduce fuel burn.
With a Turboprop it is probably less clear cut, but using two engines instead of four should at the very least reduce the maintenance bill.
If you can standardise the engine design so it is used across a range of big aircraft types you will save money too, but for a bomber the peak times when you need high power is during takeoff and penetrating enemy airspace. With long range cruise missiles that means the peak engine power is needed only for take off at max weights... after you have climbed to operational altitude then you cruise to your launch position and launch and then fly home.
Having two engines instead of four reduces drag, and is a better solution as long as the two engines are powerful enough so that the aircraft is not made underpowered with the loss of two engines.
The articles posted correctly state that it's a more expensive & unaffordable option than building IL-106s.
But the Il-106 is a smaller lighter aircraft... of course building more An-124s would be more expensive, but they are also more capable and able to carry more further...
Not if the cargo is bulkier, longer & over 5 tons!
The Il-276 will have a payload capacity of 20-30 tons...
For example, if a few big helicopters, TELs/OTVs/boats must be moved, it's better to have the Y-20s than IL-76s.
Well obviously for bulky large objects needing to be moved a bigger aircraft makes more sense, but in the real world really big items normally move by ship anyway. And they have helicopters that can carry slung loads of all shapes and sizes...
NATO used mostly the An-124s; it has enough C-5/-17s & commercial freighters for less demanding logistics. If it was so adequate, they would just stretch the IL-476 & add more powerful engines to make it = to the C-17 in payload, for a fraction of the cost of the IL-106.
Did you check that or is that just opinion? Because for a long time during the 1990s they used Il-76s because the C-141s are crap, and the C-17 are absurdly expensive... and for smaller loads the C-5s are also too expensive... just like the An-124s are for smaller loads.
The evidence has come a full circle: the IL-106s r to replace the An-124s!
Perhaps it is an understanding thing... the Il-106s are to replace the An-22s, the An-124s are currently being used in that role right now, but are big and expensive to run for such payloads.
If all you have is a mini and a two ton capacity truck, when you need to shift a barbecue, you don't use the mini... it would be easier with a small van or ute, but if all you have is a truck and a small car you have to use the car.
You can say the new van is to replace the truck, but when you need to transport whatever it was you needed the truck for in the first place you wont try using the van, you will use the truck.
BTW even if you could fit an Iskander into an Il-76 transporter, you still need the command vehicle and other support vehicles too, so even if you could fit the TEL into one Il-76 it would need several aircraft to deploy a unit.
At 40 tons the Iskander TEL could easily fit in an An-124, but more importantly you could also fit some of the other vehicles from the unit... the data preparation vehicle, the command and staff vehicle, the transloader, and the life support vehicle and the maintenance and inspection vehicle... it is still not going to be all in one plane as the transloader will be the same weight as the TEL...
With the Il-106 you could probably get the TEL and transloader into one load, while a second aircraft could probably take the other four trucks as they are smaller and lighter... in fact the other four trucks would probably fit into an Il-476...