The odds are good everyone will be waking up on Friday feeling disappointed.
The Tories will have exposed serious flaws in May, and hacked away at their high approval ratings, for the sake of just a few more seats. Her judgement looks appalling. The decision to call an election was very stupid. She's committed a series of unforced errors. Gaining 10 seats or so is/was not worth it and everybody knows it. The shine is totally gone from her premiership and it's nobody's fault but her own.
The Lib Dems have had an enormously disappointing campaign and their renaissance is not forthcoming.
The SNP is likely to have lost a few seats - again, disappointing. Harder to justify IndyRef2.
The Corbyn wing of Labour is disappointed because as far as they are concerned, JC ran a great campaign, and if the "Blairites" had only backed him properly instead of spending 2 years undermining him, they could have won. He will not go quietly into the good night. Cue 2-3 more years of Labour writhing about in vicious leadership contests.
The centrist wing of Labour is not happy because Momentum is not going to fuck off any time soon.
Basically nobody wins. Unless there is a massive polling error (possible of course but unlikely) and it swings 4-5 points to May or Corbyn, giving May the 40+ majority she thought she had in the bag, or giving JC a hung parliament which is miles better than anyone could have expected.
But the statistically likely option is that everybody has failed. Whee, what a jolly start to the Brexit negotiations.