New gTLD single letter second level domains were sold for low-mid $xxx+ in the past.
I believe this is no different.
Only domainers(resellers) may show interest in such new gTLD.
Resell price: low-mid $xxx
End user price: low-mid $x,xxx+(when the new gTLD gain attention from end users).
If you wish to flip it and earn money fast, you can sell it to a reseller at Flippa.
But if you wish to earn more in the long run, waiting for 4/5 figures End user, you will have to wait for years.