The key will be how much SNP MPs are able to get accomplished federally. If they end up sitting in Westminster purely as ineffectual "protest MPs", expect them to be voted out eventually.
In Québec's case, lots of people simply said "ok, Quebecers are just going to vote in the separatist party every federal election no matter what we do, and those separatist MPs are never going to be relevant, so we can just safely ignore Québec." Eventually, Quebecers realized that their strategy was backfiring, so they started electing federal parties again (but staying non-committal to any particular party: making damn sure that those federal parties took Québec's requests seriously, else they would vote in someone else in a heartbeat). Of course, this strategy might be more difficult for Scotland (~10% of UK's population) to make work compared to Québec (~25% of Canada's population), due to decreased leverage.
The lifespan of Holyrood's SNP will probably be a lot longer, although they will probably lose a bit of their current stranglehold soon. Québec has its own devolved government too (as all Canadian provinces do) and a provincial separatist party (sister parties with the federal separatist one) dominated provincial politics there for a long time too. While that party still polls decently across the province, they have only held a single minority government since 1998. People eventually started saying "yeah, I still support independence, but the separatist party is not doing enough to fix the economy (e.g.), so I'm going to vote for [insert "normal" party here] instead." Over time, other issues will come to the forefront in Holyrood, and the SNP's pro-Scotland rallying cries will get pushed to the backburner as voters turn their attention to other issues deemed more important.
Or, I could be full of shit. During the Scotland independence referendum, every Canadian was saying "yeah, we've seen all this before" (and the nature of the campaigns + the result played out exactly as it did here), but I'm not actually sure how much of our situation is applicable. Who knows? =P