Highly unlikely in my opinion. I expect McLaren to exactly follow the 570S>600LT paradigm, in other words factory body kit, top exit race exhaust, small bump in horsepower, and MSO roof scoop option. I'd expect the wing to remain active but maybe redesigned to be more aggressive. Weight reduction of course too, although I'd guess < 50kg compared to a 720S configured with minimal weight options - there just is not much fat to cut on these cars. It seems likely that all cars introduced after the 720S will have hybrid powertrains, so very possible the 7XXLT might be the last McLaren running solely on gasoline.
That said, McLaren could unexpectedly drop a new hybrid series production car in the $500-600k range to compete with the SF90 Stradale... basically a detuned/simplified Speedtail drivetrain dropped into a car built on the 720S platform, just like the mules we have seen. Without the requirement for 250 mph VMax, flexible carbon fiber, center steer configuration, etc. and with say 1000+ rather than 106 units produced, the price could drop right into that target range. Only other new car occupying that price segment is the Aventador SVJ, which is lacking in performance outside the Nurburgring, and maybe the FGT too although it's also an underperformer and not something you can just walk into a dealer and order if you have the cash. If McLaren indeed did this, it would not make sense to sell it as an 'LT', as that moniker is reserved for low weight, track-focused cars. Hybrid will add hundreds of pounds, it would be called something else entirely.
I do think McLaren found a sweet spot between power, weight, and efficiency (drivetrain and aerodynamic) with the 720S. The extra power from hybrid designs comes with a big weight penalty and I'm not convinced it will be worthwhile. And you can count on spending 10% of the original MSRP in 6 years when the high voltage battery is toast.