The question assumes that tens of millions of dollars will be spent by the county on a countywide water supply system, with the result that parts of the county will never be inside the city limits . In other words, there will be a kind of boundary line beyond which the city can never expand, almost a demilitarized zone. I do not want that.
As home building companies develop new additions in Midland County (especially precinct 4) and the city expands into the county, the 3 mile ETJ (extraterritorial jurisdiction) also expands into the county, moving the city limits further out, increasingly encompassing what was once outside the city limits. The city may never swallow the county, but the city will grow.