[EffectiveSprinkles]

Right then, in my view F1 doesn't need as much 'fixing' as it needs to reflect on what's been done before and what other solutions are out there. Consolidate the good, get rid of the bad. In my line of work I tell companies that they can improve their results by 200% with the same amount of people and in half the time. They don't believe me until it happens. F1 is run like a big company these days and they are always tempted to ignore what they have and focus on trying to improve or tweak. In my philosophy, a lot of things can't be 'fixed' or totally gotten rid of, but can be migitated or diminished. It doesn't always have to be either fully allowed or fully forbidden, compromises can exist. Having said that;

Technical side
Leave the engines (sorry, 'power units') pretty much as they are, this is perhaps one area where only tweaking might actually work. The packaging is extremely tight due to the too strict aero regulations so that needs freeing up. They would sound better with a proper exhaust, so exhaust regulations need to be scrapped. If a team wants to allow a blown diffuser, let them. Scrap the 100kg/h (or 105 as I think it is now?) fuel limit and adopt the same regulations as WEC LMP1. Fuel limit per 3 laps of a representive circuit with a per circuit modifier. This will limit (but of course not completely erase) the amount of fuel saving needed.
Cars are too heavy and too wide. Go back to 2008 dimensions as much as possible, ignore everything the regulations for 2009 and 2014 asked for. It was the wrong road to take and that should be acknoweledged. The current cars are abominations because of trying to 'fix' the dreadful 2014 rules instead of starting properly from scratch. Replace the halo with a windscreen.


Aerodynamics
Leave it as it is, although again looking at the 2008 rules for inspiration would be best. Realistically speaking however, leave the regulations after the 2019 changes to the front wing (which won't make a difference anyway). DRS stays. Stability is needed. Do NOT listen to the zealots who claim the cars have too much downforce, that nearly destroyed F1 as we know it back in 2009 and again in 2014. This is probably more a sporting thing but I'll put it here: DRS can be used whenever you're less than a second behind someone. If you're not, you can't use it. No more zones, so that if you pass someone with DRS you can't use it again in the next zone like it is now. No DRS in qualifying.
Free up the exhaust regulations as mentioned above. The 'coke bottle' design needs to go, it limits engineering freedom for the power units. If that means blown diffusers will become the norm, so be it. That can be migitated somewhat by mandating the exhaust exits be visible and above a certain plane. Again, compromise. Someone might invent something that works better even. Also let's hope all this gets rid of the ridiculous noses we've been stuck with since 2010.


Tyres
Oh boy. This needs a total rethink. Almost everything that has been done since 2011 has been a complete waste of time regarding this issue. Whatever the intentions were, micromanaging this issue will never ever work. It's pretty much the biggest problem I have with F1 in the last decade or so: trying to throw all sorts of random curveballs in the hope it trips up the top teams and upsets the applecart. Except it never, let me repeat, never works in the long term. If it does it only does so for a very short time. Lots of people rave about the start of 2012 and how many different winners we had, but I mostly remember the proper championship fight we had after the teams sorted themselves out again and the tyres worked somewhat. So my proposal: copy MotoGP. Seriously. They have three front tyre compounds and four rear tyre compounds. All of them can last the entire race and the riders can choose any combination they want. Every compound is available at every race (though because they're motorcycles they do have asymmetric tyres for tracks with a skewed corner distribution, this is not relevant for F1 and the compound of the main part of the tyre is still the same). I have much more to say about this regarding the sporting side of the tyres but I'll leave that to that section. This will also make the entire thing so much cheaper since Pirelli doesn't have to chase some sort of mythical performance or degrading window mandated by the rules and can just do what they should: make tyres. If needed for the show, a special qualifying tyre can be produced that only gets used in Q3 and cannot be used in the race. Let's see how fast these cars can go (without DRS).