Rostov-been-Droned was hit when it was in a Sevastopol repair facility, not while at sea.
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So the possibilities range from it being beyond repair to repairable to slightly (or not at all) damaged and submerged by its crew's choice. Hence my comment above that it may take a while for information to be released or leaked to learn how badly Rostov-on-Don was hit.
That Kilo-class submarine
Rostov-been-Droned was sunk - and still is - in-harbor has been confirmed with satellite imagery.
https://www.youtube.com/watch?v=fQzd_nsKCcMWhether it is unsalvageable is not known for certain, but a week and a half underwater has obviously not been good for machinery and electronics, at the very least. Sevastopol is not exactly the safest place to try a large-scale salvage project, so that makes salvage even less likely. Whether she's unsalvageable or not,
Rostov-been-Droned will be tying up valuable harbor facilities for months to come (it took nearly a year and a half to right USS Oklahoma, patch her, and tow her out of valuable mooring space), even if she's promoted from obstruction to artificial Black Sea reef.