It will be very interesting, if they use a good lc0 engine and a good net. As we saw, Jonny on 2400 distributed cores and GridGinkgo on 224 are no better than Komodo on 48 Intel cores (several CPUs). If we take Komodo 12+ on 48 cores as the bench to be among the best, we can extrapolate and foresee a bit of how it will look like.
Komodo 12 on CCRL 40/4' is about 3450 Elo. Leela (lc0) on my GTX 1060 GPU with one of the latest nets in the main branch is at least 3300 Elo CCRL 40/4'.
Leela on 8 x Nvidia Tesla V100 gets maybe (depending on parallelization) about 20-30 the effective speed-up compared to my GPU.
Komodo on 48 Intel cores gets probably similarly 20 or so effective speed-up compared to one i7 core.
So, hardware-wise, we can compare simply Leela on my GPU to Komodo on one i7 core, as I did getting 3300+ CCRL 40/4' rating for Leela (lc0).
Effective time control on i7 core for 4' CCRL is 2' (CCRL has as a bench a 2 times slower core).
Time control in WCCC is 120', or 60 times longer (6 doublings). Each doubling adds at this long time control about 30 Elo points to Leela compared to Komodo (Leela scales better), so the rating of Leela at 120' LTC is about an effective 3480, when compared to very comparable 3450 of Komodo.
All, in all, Leela in the best conditions, would be on par with the best there (probably Komodo and Jonny, but maybe Ginkgo and Shredder can come close too). But this is from regular, solid, short openings I used. Leela has a property to be very weak on tactical puzzles and misses often in endgames easy wins or draws. While the endgames are addressed in this 3300 rating I get, my openings do not reflect the fact that in WCCC one can use own custom opening book. This can be huge in the case of Leela. If the people there will prepare anti-Leela tactically very sharp opening books, Leela can underperform by as much as 200 Elo points. I just performed a test where Leela (lc0) with a good later mainbranch net got slaughtered by Komodo 9.2 from tactically very sharp opening positions collected from ECM879 suite. While from quiet regular positions, they are pretty much on par in these condition (40/2'). The difference in performance was 200+ Elo points using these two different opening suites.