I worry that another poll will need to be made to re-increase the amount pointed at debt repayment if it starts to take too long.
That won't happen. If anything, we've been paying way over the 25% of mined coins that were agreed. When an automated system gets put in place, it will only pay 25% of mined coins. Any coins generated from minted seats, donations, or the pool, will be distributed normally so that NastyMining can rebuild BTC holdings.
The only thing that rubs me the wrong way with your explanations is bringing in the USD conversion rate. What the conversion is now, compared to when the loan was made should have no bearing on anything. As I doubt you would double the amount of BTC returned to them if the conversion rate was to drop to $50/BTC. But as you mentioned you have no intention of forcing people to accept less BTC then lent, so I hope the lenders are still feeling okay with their involvement.
The USD conversion rate very much exists. Fact is, we took lended funds and dumped them into orders denominated in USD. That very much has a bearing on things. For example, there isn't a legal entity on the planet that would recognize the amount lended in BTC and not USD. As the largest lender to the organization, I take that into account. Considering the amount of funds that I lended were so much lower in value than what I am owed today, I would happily accept much less in order to be repaid and see a substantial profit in USD. I didn't lend funds to NastyMining at 0% interest to make 10x the fiat value, I lended to help the organization. Perhaps I am alone in this thinking, which is why I am not forcing anything. However, every time this comes up I will state that I am the largest lender and am willing to take a significant reduction in BTC owed in order to accelerate the payback. Perhaps some of the other lenders will start feeling as I do and talks can begin on how to handle this issue in a way that satisfies everyone's best interests.
Your example of the BTC drop isn't as drastic as the real situation. I believe that if we were lended BTC at $100 and the price fell to $10 after orders had already been placed, something would have been done to try and make the situation right. That is part of what makes this organization so great. We aren't out to screw people like others who offered fixed MH/s rate bonds when I started this. Remember that there was a time when people were on the fence whether to buy a NastyFans seat or a 1MH/s fixed rate bond for the same price. It has always been good faith that kept this organization alive, and I don't believe I've ever done anything to damage that faith. My opinions about the debt are just that, my opinions. At no point have I ever made any proposal or tried to intimidate anyone into accepting less than was promised. I simply think that if everyone looked at the risks/rewards, they might be willing to accept less in order to accelerate the repayment process and I have no qualms about being open and honest about the risk or delay in waiting for full repayment. I am also not suggesting that the debt be repaid according to the USD rate at the time it was lended. I am merely stating that an agreement with all lenders on a reduced BTC amount would allow everyone to see gains in USD much faster.
It should also be noted that my opinions on this matter are being solicited, and I am not proposing any change to the current repayment of debt.