Would really be nice if people would stop assuming there is an IMSA partnership solely based on a car from 2018. We got a Lexus RC F GT3 from GT Open and that didn't mean squat. This feels like its quickly becoming the new "That car is coming to GT" just because someone saw a GT windshield banner.
On this subject. I'm not saying there will be an actual 'partnership' with IMSA, and this post is purely speculation on my part. As such I recommend readers take what I say with a grain of salt. I know I don't have the concrete answers.
It at least 'seems' (italics aren't working for me right now) to me that there is at least 'some' content coming to the game that has connections with IMSA. Here's my speculation points:
* Daytona is coming back. That much has been confirmed, however literally nothing so far about NASCAR or other oval-specific cars in GT7, at least at this time. The Rolex 24H is the biggest race that the road course hosts, and it happens to be part of the IMSA Endurance Cup.
* Road Atlanta being found in the code of GT Sport. I kinda saw the possibility of it coming to the series being higher ever since the Michelin partnership featured the North America branch in the live stuff, who now also own the circuit. A bit of a side note but JP Montoya was driving a Michelin liveried Honda NSX Gr.3 at that live event. He was driving for Acura Team Penske at the time in real life, but besides that nothing particularly of note to do with this topic.
* Watkins Glen was found added a couple of minor updates ago too. That means that 3 of the 4 tracks featured on the IMSA Endurance Cup calendar have been found in the GT Sport code, and in Daytona's case in GT7's circuit menu too.
* The missing track to get all 4 of the IMSA Endurance Cup tracks, is Sebring, which has no concrete evidence outside of this speculation (which isn't concrete either, hence it's speculation) of showing up.
* Now this is going VERY far back, and as I can't find the source don't quote me on this, but I recall there being some news (maybe something from a GTP article, I can't remember) that PD were at one of the IMSA races (Possibly the 2018 Rolex 24H Daytona) scanning and getting images of several GTLM, and even DPi cars. You'd think PD would probably have scanned a WEC Ford GT given their FIA connection, but as soon as I saw that this was the IMSA GTLM version it got me thinking back to what I heard, and if that news about PD scanning multiple IMSA cars has some substance. This might still not be the case however, and this Ford GTLM might be a one-off as RACECAR mentioned with the Lexus RC F.
That's pretty much all of the jigsaw pieces of speculation I could find regarding IMSA stuff and GT7. There's quite a few things, but again nothing is ever concrete until we see it in the game for ourselves.
Make of this speculation what you guys will. Remember it is just speculation. I don't have the answers.