Well, I'm not going to beat about the bush here: there are some worrying straws in the wind to be found in recent Scottish subsamples from YouGov. The last three have had the SNP down in the 30s, which is unusual in recent times, and two of the three have put the SNP below the 37% recorded at the last general election, which is highly unusual. This looks like the manifestation of what I've been worried about since it became obvious that Jo Swinson would become Liberal Democrat leader. A Britain-wide party led by a Scot has an inbuilt advantage north of the border, because that person is all over the UK news in a way that the SNP leader is not - a problem that will only get worse during the official campaign.
This is the newest subsample...
SNP 35%, Conservatives 21%, Liberal Democrats 20%, Labour 11%, Greens 6%, Brexit Party 5%
It's quite hard to judge what a result like that would translate into in terms of seats. The SNP would be making heavy gains from Labour, and at least modest gains from the Tories, but it's very unlikely that the Lib Dems would only be winning four or five seats on 20% of the vote. They'd probably recover a lot of the former heartland seats that they lost in 2015.
Of course the Greens won't stand in every seat, so some (but not all) of that Green vote can be regarded as the SNP's for the taking...but then again the same may be true in respect of the Brexit Party's vote and the Tories.
I suppose the bigger picture is that this still looks like it could be the election in which Scottish Labour cease to be a major player - and that could mean sustained SNP hegemony under first-past-the-post.