Any town whose land values no longer support the rehab/renovation of existing SFD is in a bad way. If there is zero demand for existing housing that can be restored using sweat equity, there is zero demand for (new) infill housing. What could be saved is pretty much irrelevant. Non-market infill development makes things worse--competes with existing housing. New multifamily isn't feasible. NIMBYism preventing existing SFD from being converting into multifamily is making the blight worse, because rather than having duplexes you have abandoned and decaying single-family-detached.
Fighting blight through demolition just creates pockmarked areas. Demolition of blighted structures just changes the flavor of blight - from building to lot. The core issue remains - insufficient demand. You can't cure a lack of demand by adding additional supply. You can subsidize non-market infill housing in the name of 'neighborhood stabilization'. Which will work, but only by strengthening a political constituency capable of advocating for infrastructure investment near them, to the detriment of other neighborhoods, such as has happened in Chicago.