No idea, but I would expect that the Russians will maintain a stockpile of at least 2-3k Iskander M. They are busy building new armies in the rear as reserve forces in case the incompetent Russophobic clowns in EU/NATO do something phenominally stupid and a broad continental war breaks out. The idea they will retain ~700 ballistic missiles of all types when such a scenario is a real risk is quite frankly totally bonkers
BTW I've read Ukropi estimates that Russia builds ~65 Iskanders per month and maintains a stockpile of 100-150 units. More stupid numbers they have sourced from their collective rectal cavity... in true NATO fashion.