I do not like Steam but I recognize it has way too much more benefits compared to the bad side. And I sure can't find anything "detrimental to the gaming industry"
What I mean is:
ISI update the graphics of current engine and make it more "mainstream" (but no need to put everything the mainstream games is adding, and whatever is used make it possible to be turned off, I'm sure 90%+ of players would be happy with this). And move to DX11 or12 or Vulkan, whatever

Add some detail stuff such as pit animations, etc
Now this is not a base for moding anymore
ISI starts an service like iRacing for online racers... but trying to make the monthly payment cheaper because...
The sim is now the Steam of sim racing. (please keep in mind the studio names are just examples, let’s avoid some stupid discussion on this...)
Sector 3 renew their DTM and/or WTCC licenses. They don't need to make a new game, they can sell it inside ISI "Steam". The deal between them could be like ISI get 10% of each sell to keep evolving the product and improve the AI for example.
Sector 3 also has some GT licenses now, let's say 5 or 6 cars. They also sell it as a pack
Sector 3 has license for many German race tracks, they can sell a German Tracks pack too
Reiza has Stock Car Brasil and Copa Petrobras de Marcas license, also sell it on ISI “Steam” with a deal, maybe different from sector 3 as it is less known series worldwide.
Reiza also has license for many Brazilian tracks, could also be sold as a pack.
Let’s say now instead of paying for ADAC license Sector 3 could go to ADAC and say “look the cool cars and tracks we have in this game... we want to make a german online championship, if you sponsor it we could tall this the...
( •_•)>⌐■-■
Virtual ADAC GT Masters
(⌐■_■)
xD kidding, or not...
Focus on track packs per country because you can have national GT, F3, Touring cars, etc series and get the best guys from that season and put them all together in a world league
Other studios or even the same guys with products already in this “Steam” go for LMP2, GTE cars, French tracks, British tracks, ovals in US, historic cars, getting the new models from the current cars already in the sim (like GT3), some could also release single cars/tracks, hot rod packs, dirt, dragsters, street car packs, drift and so on
No idea how good this would be for devs and studios but I sure would like it as a customer

that's the kind of "steam of sim racing" I'm talking about
Mods... sorry for the off topic ^^"