A listing of seats purely by swing to win is not the same as a listing of future target seats as other factors come into account too. It does however give a good overall picture of the territory over which the next election will be contested.
So courtesy of Phil Rodgers on Twitter, this table is worth some study:
Given that the Conservatives and (in Scotland) the SNP are in government, and it is usually easier to win seats off the government than off other opposition parties, the predominance of Conservative and SNP seats in this list is helpful.
Also worth study are these two extracts from the House of Commons Library’s report into the 2017 election (in full below), especially the way the map of Lib Dem support does not obviously match up with the map of Remain support across the country – a sign of how the Lib Dem pro-European message did not work or a sign that the pro-European message was the wrong one? That’ll be debated I’m sure during the forthcoming leadership contest, especially if Norman Lamb (a rebel on the Article 50 vote in Parliament) is one of the runners.