Stormfront Lite is beside itself with excitement this afternoon about a Populus analysis suggesting that the SNP would lose all but six of its seats at the next UK general election if it found itself tied with both Labour and the Tories on 30% of the popular vote. (Labour would have thirty seats and the Tories would have eighteen.) The problem here is not so much that the analysis is wrong (although it might well be - how the votes for each party would be geographically distributed can only be guesswork), but rather that the scenario it's based on is pretty implausible, and therefore not nearly as interesting as is being made out. Even now, when we have a reasonably tight three-way battle, it looks like the Tories have slipped to third place, and it's very hard to imagine a situation in the foreseeable future in which they'll by vying for the outright lead or even for parity.
Much more likely is that 2017 will prove to be Peak Tory, and that Conservative support in places like the North-East is going to gradually - or perhaps not so gradually - drop back as the realisation hits home that Tory voters were actually voting to help keep a dire Westminster government in power, rather than for the Ruth Davidson Strong Opposition We Said No And We Meant No Party. If that happens, it's difficult to see how the SNP aren't going to regain seats from the Tories, even if they're locked in a tight battle with Labour nationally - or indeed even if Labour move into a clear lead. What we could see is a repeat, albeit on a more dramatic scale, of what happened in 1987, when the SNP lost two seats to Labour, but made up for that with three spectacular gains from the Tories.
That translated into a net increase in overall SNP representation - whether we'd be so lucky this time is debatable given that there's much more to lose to Labour than there was three decades ago. But predictions of one-way traffic against the SNP just don't pass the smell test. The Tory surge of 2017 may have been much smaller than the SNP surge of 2015, but the two are probably pretty similar in the sense that they were both relatively sudden, were caused by very specific short-term circumstances, and perhaps involved voters who didn't have any real depth of commitment to their new party. I expect the tide to recede for the Tories at the next general election, and the party ideally-placed to benefit from that is the SNP. There is no other credible challenger in the vast majority of Tory-held seats.