"continuing a product that costs more to maintain than the revenue it creates is unsustainable"
This is true, but this seems to have been done in a dog in a manger way. There are better alternatives.
There could, as another commentard has said, have been a final update that remove checking. That would have cost very little effort and given those who've paid over the years something permanent for their money. AIUI if they need to replace hardware - which they will at some point in time - they can't take it with them.
Source could have been placed in the public domain.
At the very least there could have been an apology to customers who have been dumped.