I am flying LHR-DME-TAS shortly, BA then S7 on a single ticket. The layover is 1h10 and BA required 1h0 before issuing the ticket, so that is all good. I do not have a Russian visa as one is not required according to their transit rules. My question is what happens if my inbound is delayed? Not from the POV of BA/S7 sorting things out, but rather from the POV their limited options.

There are several later flights, but all have a Russian domestic stopover, so those are presumably not an option with no visa. The next S7 service is three days later. The only other direct flight in the 24h no-visa-required grace period for DME is with a non-partner airline (UZ Airways). But what happens if that has no availability and I'm now over the 24h grace period before I can get an onward sead. An interesting conundrum.