I think TTT's nailed the description of the 2017 election. One other thing that marked it is how the meteoric rise of Labour wasn't really associated with a corresponding fall in Tory support, which stayed more or less the same, in the low 40s, right through the polls and into the election. It wasn't really a Tory collapse, but a failure to win former UKIP voters (and the younger voters) that cost Theresa May her majority. Still a stupid election to call and a disastrous campaign, but I don't think it would have taken many swing votes for it to have instead been the biggest Tory win since 1983, so... fine margins!
I don't know what this means for the next election, though. Labour have an opportunity now to actually unite around a clearly successful and electable leader, whereas in the run-up to 2017 they were a party in disarray, while the coming years will see the fallout from Brexit. If May does a good job, she wins (by a landslide). If she doesn't, then Corbyn will almost certainly beat whatever the Tories have to offer, because General Elections offer the only realistic opportunity to hold the incumbent government to account.