That's a pretty great layout for Hockenheim. I can see one putting up grandstands on the outside of the complex on the bottom right and clearing the trees away from it so that the fans there can see everything going through the whole complex.
I wouldn't need to clear that many, considering the clearing created for the (OTL named, forget pre-1994 name) Senna chicane. That was the general plan, btw.
If I may make one suggestion, to make the new Ostkurve one that is tightest at the beginning and then opens up. At F1 speeds, that will alone make accelerating out of it a challenge (thus also effecting the speeds on the straight that follows) and will allowing passing maneuvers into it. Making the approach to that corner quite wide would also be a good idea, allowing different lines through that corner. I can see several legitimate passing opportunities in an F1 car there, which is a very good thing.
I had been toying with using the first half of the Clark chicane as part of Neue-Ostkurve, so consider that part of the canon layout circa late-90's TTL. I'll just delete the first 1/5 or so of the "transplanted" turn, and use that sharp right-hander (albeit widened) as the opening segment of the turn. That'll involve pulling back the radius of the whole turn, and I'll be making a more curvy "straight" from that to the right at OTL-Senna
The greenies will hate all of the trees torn down, but I may also make the suggestion of keeping the old track intact for sports car and touring car racing where speeds are lower and thus safety is less of a concern.
Come up with a plausible (and generous) sop to the Greens and I'll make that canon, too. I've been stumped, the closest idead I've had on that score was to find some rich entity pay to demolish a large run-down neighborhood and fill it with trees, or purchase any neighboring properties to the forest and reclaim that area.
I actually admire the German Greens making a stand about Hockenheim, though. I've been there, and the woods out that way are worth putting some spine into protecting.
Personally, if Bernie and the FIA weren't so keen on shorter tracks and sub-two hour races, I'd have "Mosleystone" tell the teams to make their cars more crashworthy and have better endurance, with better runoff and safer barriers around the turns, and turn the German, Italian, and Belgian GPs into 500km races with all chicanes removed. Folks in the stands would see a couple dozen more laps, the fun way! I don't see that as plausible ITTL, the POD is too recent and the momentum towards what we have now is already present.
As far as layout changes, I mentioned what I'd do with Surfers Paradise.
I'm pretty much doing it that way.
I don't know what you'd do with Cleveland,
Flip the front straight and the pit lane to delete the chicane.
Watkins Glen doesn't need it in all honesty
Minor changes here: Lengthen the straightaways between 9 and 10 and 11 and 1, (at the expense of a sharper turns 10 and 11. The exit of 10 would branch off to pit-in.) This will be to increase the length of the pitlane, which I'd want to do to fit a modern F1 paddock in for a bid to bring Watkins Glen back on the F1 calendar, without having to rush the job trying to get construction between races and inclement weather. I want to have IndyCar's war chest preserved for other expenditures, so such a move would have to be done right the first time.
Portland had the problem of the fact that the track is in a park, with a highway to the east, a river to the south, a golf course to the west and a preserved wetland to the north. Adjusting through the golf course is the only one of those you could do, and that would completely mess up the layout.
-Flip the direction (all turn references are OTL so a wiki map won't lead to confusion, though.)
-The complex of 10 through 12 would be tightened up in the 11-12 end to create a passing zone, and loosening up between 10-11 to create a technical section which will impact battles down the straight.
-Delete turn 8 and straighten out the section between 7 and 9.
-Lengthen the straight between 6 and 7 slightly, and tighten 6 accordingly to feed into the 4-5 section.
-Possibly, (leaving this up for debate,) rounding off 4-5.
-Delete 1-3.
(Appearance by Captain Obvious) I hate chicanes breaking up straightaways or used to replace what would be a good 90-degree or hairpin turn. When used in a slower section, they're freaking awesome.
As far as the Tilkedromes, you just have to have him do less of the slow corners. Your proposed lower-downforce F1 cars will be better for racing and won't turn as fast in high-speed corners in any case, so the faster corners won't be as much of a safety hazard or racing impediment.
I have nothing against slow corners, as long as they're used properly, and don't make the races sterile and processional. Take Sepang, personally, the only thing I'd change about it if I could would be to lengthen the straight between 8 and 9. The corners work because they flow together. Same for Shanghai (I forgot he did that one when I posted earlier about Tilke.) Now for the others: (warming up for a rant.)
A1 Ring: Broke a great track, not enough passing opportunites. Westschelief proposal looks awesome, though.
Sakhir: Uninspired but has potential with minor tweaks.
Marina Bay: Seriously, turn 10? Too many point-squirt-brake-repeat with not enough passing.
Valencia: *yawn* Release the Grosjean!
Yas Marina: Can be made middle-of-road to good track with minor tweaks, but in current form it's sterile.
Yeongam: About the same as Marina Bay. The only reasons I remember anything about any races (last year was the only one I think I stayed awake through lights to flag,) was Hamilton picking up the astroturf and Massa getting told to back off. Seriously, it's like Tilke wanted to make a great track, and gave up after turn 6.
Buddh: Minor improvements needed to greatly improve the track. Delete 7-9, and round off 6 to line up to 10, then reverse the direction, and it could be epic.
COTA: "Oh, the Americans won't know better that I just decided to cut-and-paste a track together. All they know is left turns." Of course, you put a turn like Hill in, add Maggots-Becketts-Chapel, throw in Hockenheim's Stadion, and drop in the Diabolica, it's pretty hard for there to be bad racing. The obvious ripoff just comes across as insulting.
Port Imperial: Looks worse than Valencia. Reversing direction would put it in Marina Bay territory.
Sochi: Could use deleting 15 and 16, we'll see how it is next year.