Hmmm, I didn't even mean to consider those with large debts, harder to draw that line. Student loans are easy enough to pay off, at least federal loans with low rates, compared to crippling 20%+ interest credit card debt. But reguardless, I'd say if you can manage to make whatever obligatory payments you have, and still have enough left to eat, cloth, and keep a shelter over your head, you'd not be 'poor' in this scenario (again barring major humanitarian subsidies).
Along the lines of this morbid train of thought, would there have been as much of an outcry if Hitler decided to kill people based on economic value instead of race/religion? Round up all the poor performers and throw them in forced labor camps, etc.
I feel like in most systems, if you cut out he under-performing subset, you effectively raise the overall average. In this case, sure the current middle would then be the "poor" but after the initial purge you'd be left with more productive members of society... But the problem of filling low wage jobs is quite an issue. You'd really be forced to pay those people livable, comfortable salaries to entire people to work them. It would be like suddenly raising the minimum wage to $25/hour. In order to pay for that, companies would have to drive down costs, which would either be finding exceptionally cheap labor abroad for those industries that could, or otherwise relying on the gov't to help them pay the wages of the people now keeping the country running. Thus, increased taxes, punishing those that make money, driving top talent out and away from the country. Then of course the issue of paying the guy cleaning the sewers the same or more than a corporate job, why bother getting an advanced degree.
In a capitalistic society, there doesn't seem to be a way to functionally get rid of the poor economic class for good. You need them to be poor or the system fails. Are all economics a zero sum game like this?