Your first sentence discredits everything else that you have to say...because it is well known throughout the Vgchartz community that ethomaz is the biggest GT fan alive lol :-p

As far as I can tell there's nothing forcing you to use them, not every means of digital distrbution is guaranteed to go the way of console DLC.

To remain relevant for me, personally, they need to fix a few things:

The sound, the engine sounds in GT games are pathetic in general, some very few sound great but most make either no noise at all or an audio equivalent of the beige you get when mixing all colors, a sort of indistinct hum.

Tuning, more of it and more potentially extreme fits, perhaps at the cost of durability. Juicing up the power or other features while increasing the chances of mechanical problems would be cool and realistic. Being able to extract only about 650-800 horsepower and a moderate amount of torque out of some of the best tuning cars in world is a downright shame and the mechanical aspect is non-existant save for tyre wear, changing oil and filling up gasoline now and then during endurance races. How about hiring and maintaing your own team of mechanics and engineers? Different tuning providers that favor power over durability, some specializing in diesel or hybrids, some being better at aerodynamics etc. Depth and realism right there.

B-spec is ridiculous but if you want a system where the player can make money, why not simply implement a system where you can "sponsor" an AI racer and get a stockmarket inspired profit now and then based on different factors. Or how about being able to combine into racing teams with other players via PSN, joining leagues, adopting or sponsoring other, newer players (kind of like in Stronghold: Kingdoms, you can become a vassal and gain bonuses based on your vassal players stats and economy)?

Physics, still feels somewhat like driving a bar of soap around a mirror at times and the loss or regaining of grip feels unnatural and random. This is especially true when racing with the lower-tier tires on, no tires feel that horrible in real life, especially not on a decent car.
There's also too much focus on traction, rolling, brake shuddering and uneven pull/stop would be prevalent in old cars, basic models with poor suspension and some luxury models with less sporty adjustments.
It feels like no matter which car you drive, the only differences lie in traction in some form, this is simply nothing like real life.

Launch the whole game, why did they patch in adjustments of gear ratio long after release (just as an example)? This has always been an integral part of the tuning and pre-race setup in GT games. You could adjust the main ratio, moving the bars for the entire box but there was no option to adjust individual gears, rendering the whole thing useless since the whole point is exploiting the torque as well as possible and all engine types are different (adjusting gears for a diesel is widely different than gasoline, NA engines behave very differently from supercharged/turbocharged engines, there are also minute and bigger differences in supercharged and turbocharged).

Overall, there's a lot to be desired in the series for me, they seem to have focused mainly on increasing the car roster and making the tracks and cars look good, more than actually evolving the series and making full use of the storage capacity of blu-ray and the console hardware.
Oh, and the UI needs first aid, thing's a mess, it seems like they're sort of rebooting and returning to the roots with GT 6's UI, that's a good thing.
Yamauchi seems too intent upon expanding one feature at a time rather than lift the entire series in a steady pull, there are a lot of things missing for this to be the ultimate racing sim, especially since there are actually other relevant racing sims on the market now, as opposed to the mid 90's (on PC especially).

this right here is REALLY some excellent ideas! cause i have always loved the endurance races

More like "stay" relevant but I agree on your points.

I just want them to fix the goddamn sounds. I mean really,it can't be that hard to make the cars sound like real cars.

I agree with you in some parts since i'm a huge GT fan too but here's my argument for some of your points.

1) graphics - you say they have to up their game in the graphics department but you have not seen GT7 on PS4 yet, so you can't judge on them on that.   GT6 looks amazing and it's on older hardware aka the PS3.  I mean they added adpative tellsation on a ps3 game running via hardware, that's impressive, so i'm sure GT on ps4 would still be king graphically cause PD are amazing software devs.

2) Gameplay and REalism - i agree with you they have to up their gameplay and physics, with better sound and etc, since after playing PC sims, i selfishly want that kind of stuff in GT.  HOWEVER, i DISAGREE with you when you mention that their competitiors are getting close because GT has very few competitors, only one being Forza and maybe Project cars.   The reason i say this is cause they're really different genres and reaching diff types of people.  GT is certainly not competiting with PC sims, because GT is not meant to be a hardcore sims like those.   GT is not competing with arcade or SIMcade car games like NFS or Drive club.   GT is somewhere between simcade and hard core sim, because it wants the physics of a sim, but also wants to attract casuals.   So there's nobody that fits that genre other than Forza and maybe the upcoming project cars, thus, GT does not have much competition in  it's field.  With that said, GT being somewhere between full sim and simcade, i doubt GT will ever get to full SIM level in terms of realism because that's not the audience they're trying to attract, and they don't want to lose their appeal.

3) yes they need to improve campgain.

But with that said, i feel ike GT7 is going to be a renewal in the series and alot of things are going to reworked comepletely.  So lets wait and see.

I also want them to expand their software teams cause they do everything in house, which tends to be slower since they have less people.  turn 10 contracts other companies to help them create forza, so they're able to get things done faster.  only downside of outsourcing is other devs might not be on the same page in terms of the vision of the game and we know Kaz wants his vision to go through :D.

Yeah, it sort of annoys me, you've actually lost peak power almost with every installation since GT 2. In GT 3, you could tune a Mitsubishi GT3000 to over 1000 Bhp, for instance, while in GT 5 it packs only about 800 Bhp or so at the peak despite a few more parts to fiddle with.

As far as tuning goes, 800 Bhp is nothing, especially for cars like these that are known among enthusiasts to be able to putput some serious forces. I know a guy back in Trondheim who owns a 1000 Bhp Skyline R34 and that's not even considered very extreme. Hell, I've seen people extract over 700 Bhp out of 1.8 litre and over 900 out of an old 2.2 litre 5 cylinder Audi. Some of the V8 muscle should also be able to output truly massive torque and power, producing in excess of 1000 Bhp out a 6 litre or bigger V8 engine is commonplace, there's a guy in Norway who has a Ford Granada that pushes between 1700 and 2400 horsepower at the flywheel, depending on fuel and conditions and boost.

800 horsepower is nothing, truly nothing. The tuning in GT needs more depth in my opinion. Imagine throwing a 3 litre V6 with twin-turbo into a Toyota Yaris or something like that (would require a rebuild/compartment expansion but still).

Yeah i agree. GT5 obviously sold well but i think it damaged the brand. A lot of new PS3 ownes immediately go out and buy GT5...im talking casuals, hardcore gamers and everyone in between. ANd quite frankly most people who have played gt5 wont really go out and get gt6 in a hurry.

They need to change things up! Especially now that we are going to PS4.

i just want american cars one per gen for camaro, mustang, firebird and corvette (thats only like 30 cars!) along with drag racing mode is that to much to ask for