Why the last one ever? If you have that big a hashrate,your earnings won't be going anywhere.
As difficulty goes up, the revenue (bitcoin mined) will go down.
Eventually, the revenue will not be enough for OP to pay the rent
That was my point. With him having a large enough hashrate to pay his rent,the difficulty increment can't possibly affect his earnings in a substantial way.
Unless of course, you mean that he makes (for example) 10 000 a month mining, and only needs to pay 1 000 rent. Then an increase of 15% difficulty would only lower earnings to 8 500, still enough to pay the 1 000 rent.
That's what I meant. Sure,it's substantial,but my point was that his rent can still be paid.