Depends whether or not the city allows other neighbourhoods to exist/grow/change. If the total floorspace in the city is fixed in regulations, then ofc anything done to improve conditions will hurt people on the bottom. The people who can afford a "revitalized neighbourhood" would happily live in brand new housing built on top of land in the nearby mansion district, displacing no one, but city planners do not allow that - new apartments can only be added to the city stock by destroying old ones, new store floorspace can only be added by destroying old etc. This forces everyone to play musical chairs with too few chairs and the only winners are those who own the chairs.
I heard that in Japan, it's common for condo developers who want to buy out smaller buildings to compensate the owners with an equal amount of floorspace in the new building - not sure how common that practice actually is, but what a way to align incentives!
I think a common thing in Greece was that owners themselves would redevelop their properties much denser, retaining an apartment or two of equal floorspace to their own home, and then leasing or selling out the others to fund the redevelopment of lot.
This sort of flexibility would be really welcome in North America but SFH neighbourhoods are frozen in stone, so when the nearby high street becomes cool, all the little former working class single family homes become million dollar homes that can only be purchased by the rich, and the working class people that may have previously rented them are booted out to who knows where.