In most cities the
inner city is becoming gentrified. Young professionals are buying homes in
the city, getting strict zoning and covenants passed so they will have their
investments protected.

You can't just "pass" a covenant.
Covenants are a burden on the title, just like an easement. They work in brand
new suburban developments because the original owner of the land, the
developer, draws up the covenants for the "homeowner's association" and passes
titles burdened with the covenants to the buyers of individual homes and lots.
The title remains burdened as the properties continue to resell. A majority of
members in most HOA's can vote to disband the covenant, but nobody can come to
an existing property owner of record and say. "We've formed a home owner's
association on the other side of the street. We demand that you move your
garbage cans from your side yard to the back, take down your basketball hoop,
paint the siding one of these six approved colors, and get that boat and
trailer out of your driveway......"

At least in this neck of the woods, and with out real estate laws in this
state, y'are talking through your hat.

When zoning changes, existing uses are "grandfathered" in, property owners are
not customarily forced to tear down a structure or change the use of a property
that predates a zoning change. A zoning change will effect future use.