To the opposite, the tax should kick in if the operation is large enough. If your revenue from the game exceeds $10M, you should do some minimal continuity work. If it exceeds $100M, you should do much more serious continuity work.
I think an effective remedy for this kind of situation can't just be fiscal, we need requirements to publish adequate technical specifications and strong IP carveouts to make it likely to move the needle. Forcing companies to maintain continuous support is a non-starter. We should instead focus on enabling unofficial support from outside the companies, and remove legal threats from those who choose to do so
The idea is that the continuity requirements should not be onerous, given the revenue, say, less than 1% of it, "a good problem to have".
Publishing a reasonable spec would be a part of that.