I would be very very surprised if the DE10-Nano returns in any significant quantities now, if it does then there'll be some questions asked of Intel as to why they can fulfil orders for the silicon used on these giveaway dev boards and not the other FPGA products that are required for industry and other commercial products. I can see manufacturers buying DE10-Nanos to fit into their products if these supply issues went down that path.
I'm a contract hardware design engineer and getting anything made right now is becoming seemingly impossible, every other week I'm changing circuit designs because some IC has gone out of stock, and unless procurement jumps on a part instantly then that new design becomes unproducible quickly. I heard through one of our suppliers that the sales manager for a large FPGA manufacturer is getting a bit fed up of saying '52 weeks', as that is genuinely the fulfilment period for the majority of their silicon now.
Those on-order estimates on Mouser for the DE10-Nano are fairly hopeful, I wouldn't be surprised if they're not met.