The other asic vendors will be there long before you. As difficulty shoots up, market value of these chips per TH drops proportionally. It doesnt really matter if thats achieved by these companies mining themselves or selling their gear. The result is the same, in order to maintain sales, market prices will drop and keep dropping until at some point they meet marginal profitability - which btw, IMO is considerably lower than your estimates. If you pay $10K for a processed wafer, you seriously  need to be looking elsewhere, volume prices are ~$4K for  28nm 300mm bulk.