Yes, I agree, and I too hope it doesn't come to that.
To retain the prestige of "Legends", I think an airfield, active or not, would be the aim of TFC, in order to have visiting aircraft, and their own collection, on the ground - all part of the international attraction of "Legends".
It would initially be a big, fairly complex job, equipping such a venue for a weekend, but not beyond the realms of possibilities, and a field with intact, usable hard runways, as well as grass runways, would be more desirable, Bourn, for example.
Alternatively, an active, civil airport, with relatively low commercial movements on a weekend, such as Cambridge, or the second Cambridge field, operated by Marshalls, could be a possibility. Not the best choice, but airshows have been staged at such venues before (eg Teesside), and it could work.
My local Aero Club used to host an annual show, which was very successful, and in the "top league" for priority of acts, and that was just a small, grass aerodrome, but attracting a crowd almost as large as DX, and with prestigious "acts" from all over Europe, including the BBMF and the Red Arrows, plus those aircraft which were able to operate from the shortest grass runway used for the show (due to the requirements of the crowd line orientation), which included a Spitfire XIV.
I guess we'll just have to wait and see, and hope that a suitable location is found, hopefully in time for next year's show.