You're not going to see a GT1 Revival with this generation of supercars; 918 & P1 production is done along with the P1 GTRs, whilst Ferrari has now switched its production line onto getting the LaFerrari Apertas out and beginning the final evolution of the FXXK.
However, the sheer fact we have seen a steady increase of track-only supercars (Vulcan, FXXK, P1 GTR, Zonda R) in the last couple years coupled with the 3 upcoming supercars from McLaren, Mercedes, & Aston Martin, I could see there being more than enough manufacturer support to reshape these cars and/or the ideas behind them into top-class racing machines; they're already above par of the current GTs with unrestricted power & no rule book. Porsche could easily return back if the costs are easier than LMP-1 hybrids.
Probably wouldn't see Pagani out there (company has only so many hands-on-deck) & Ferrari only seems focused on Formula 1; they won't let a car capable of winning a top-class remain solely in the hands of privateers. Something would have to convince them they could build a competitive car & win on their own efforts.