To be honest, we will see quite a few unusual routes/airlines at LHR over the coming years as for the first time in 20 or 30 years (useful) slots there are up for grabs due to collpased international air travel. Not all airlines servig LHR are able to hold on to their precious slots by shifting from long-haul to short haul like BA is doing with the opening of some exotic routes from LHR to places like PDL or NUE.
The really interesting question is if those airlines now launching at LHR will keep those routes once air traffic has recovered, slots at LHR again become scarce and sought after and the market for slot trading is revived. If I were an airline executive, I would try to open up routes to LHR now by getting my hands on slots returned by longhaul airlines into the slot pool, grandfather those slots with the help of some start-up incentives from the other end of the route and use those slots as some sort of mid-/long-term investment that can be divested when cash is needed in the future.