The 1% per year property tax levy increase limit can be exceeded at any time by a vote of the people -- that's exactly what the mayor is proposing. The issue is that many would prefer to not have to ask the voters at all. 

It's likely that a flat-rate income tax would be constitutional TODAY -- it's just that those who want an income tax insist on it being "progressive" (higher rates for higher incomes), and it is the progressivity that is unconstitutional (Article VII Section 1: "All taxes shall be uniform upon the same class of property within the territorial limits of the authority levying the tax..."). That could be solved by simply including a high personal exemption. That is, if people actually had the political will to do it, rather than insisting on progressive rates. 

The real question, as the editorial notes, is whether current funds are being spent in ways that really work (the answer is No), and whether the new funds would be spent any better (remains to be seen).