SK
FaZe
Astralis
NiP
North
G2
Cloud9
Virtus.pro
Na`Vi
OpTic
fnatic
Cloud9
Liquid
100Thieves
mousesports
Gambit

Four seeded GSL-style groups, with either:
Best-of-one initial matches, best-of-threes for every other match
or
best-of-threes for the whole tournament

The schedule would be:

Saturday - Tuesday
Groups A-D
Matches played:
Initial matchups, best-of-three winner's matches

Wednesday:
Four best-of-threes with a rotating desk (two hosts)
Losers matches, four teams eliminated

Thursday:
Four best-of-three decider matches

Friday:
Quarterfinals, can either play out as three best-of-threes or all four

Saturday:
Semifinals, either three best-of-threes (if including the fourth quarterfinal), or two Bo3s

Sunday:
Best-of-five grand final

This adds two days to the current tournament format, but provides far better CS that is interesting to watch. I did a whole video on this idea after the last Major:

youtube.com/watch?v=b34wX4m4O2I

Possible adjustments:
Starting the tournament on Friday instead of Saturday to add a bye-day

The key reason I think the Swiss system (as it is used now) needs to go is that it literally does not determine the best 8 teams by definition. As lurppis found on Twitter, it is fundamentally flawed: twitter.com/lurppis/status/887845808506368005

I also think organizers need to get over it and start running multiple games at once. Opening the door for full best of three GSL groups and maybe a double elim playoff bracket if they are feeling spicy truly allows the best play to be showcased.

As a purist, the format is pretty much the most important aspect of the tournament. The entire goal of a tournament is to decide the best team, and that cannot be done without a proper format.

BO1

All the way

Navi
G2
EnvyUs
Liquid
Misfits
Sprout
mousesports
Virtus.Pro
BIG
Astralis
North
Fnatic
Vega Squadron
SK
NIP
Unemployed for Christmas

I think it'd be really cool to see this 24-team major but with a better qualifying system.
But, if it had to be 16 then it'd be SK, FaZe, Astralis, NiP, Cloud9, Fnatic, G2, Mouz, North, VP, Gambit, NaVi, Liquid, Optic, Vega, and 100 Visas.

I also think it would be interesting if the minor system culminated into a big 24-team international major qualifier. Either the bottom-8 from last major get invited to this, or they get invited to their respective regional minor. I would hope this would be a good way to give international experience to teams like QBF, Avangar, and Flash, without compromising the quality of competition at the Major itself.