BSI outside of Sony is mostly used to improve speed, so it's safe to assume this will be a 7D style body; something for the big field sports and wildlife shooters who need high pixel density and would be cropping anyway.
I wouldn't be totally surprised if this is more of a 90D 'all-rounder' model, since the speed could be leveraged for video too, but I'd think Canon would want to keep pushing 35mm for video for now, especially the R6. Considering that most video shoters have already moved to mirrorless anyway, it doesn't make much sense to put out another camera to cater to that audience while wildlife photographers are the one remaining holdouts still using SLRs. No other manufacturer has a really dedicated wildlife camera, and it's a demo that Canon have always had the biggest share of, so I'd imagine Canon will want to get a wildlife body out ASAP, get that market into their system before anyone else.
Especially now with the R3 out there, there will be a significant market who want that speed, that build quality, that durability and that AF, but also want more resolution 'reach' than any of the current RF bodies provide. The 7D2 still out-reaches even the R5, so something like a 28-32mp BSI APS-C sensor would really be the minimum required to get that crowd moving to RF. The 32mp sensor in the 90D and M6II is great, so if they reconfigure that into a BSI version and pair it with a better processor and a body with the durability and double card slots of the 7D... well, there's your no-brainer wildlife and long distance sports body, with nothing else on the market that could compare, currently.
BSI isn't quite cost-effective enough yet for it to be shoved into a real low-end body, and RF as a whole still is not yet ready to enter the true entry-level market (especially now a single battery is over £100 and even the cheapest 50mm is more than twice the price of the EF equivalent). Canon have made it very clear they are targetting the pros (and more-money-than-sense hobbyists) with RF first and will be getting to the lower end muchy later. Same approach as they took with EF and with the switch to digital. So anyone hoping for some kind of xxxxD/xxxD body should take another look at the industry's history, especially Canon's, and adjust their expectations.