In both cases, at least one of the rows of homes is actually large condo units on top of ground level retail space. The homes in both developments are selling quickly and in the first, the retail spaces are also condo (owner operated, or whatever you'd call it). It appears to be a mix of light food (coffee shop), retail, a fitness studio, and some small professional offices.
1 - http://www.crescentplaceleesburg.com/img/Waverly_Insert_Apr2...
2 - http://builtbytradition.com/development/developmentcurrent/j...
the other significant benefit of mixed zoning is that the city doesn't concentrate office space into pockets and breaks up peak hour travel across multiple directions and locations.
Oh wait, that's in my area, NYC. Maybe you should specify what area you're talking about too, this is a very regionally varying thing
Where I am you can get rent assistance from the council for up to 3 months. We this have lots of businesses that close after 3 months. A moderate newsagent type store on the high street is ~£5k per month (plus business rates, c.120m^2/1400sq.ft) - investors elsewhere don't need occupancy, they've already made back 100% of their purchase price in 10 years. They don't care if the space is occupied. Result, death to the city centre; it's all charity shops and pound shops.
... And like you say more shopping is moving off the high street too. But I'm not seeing the favorable high-street shop rentals you're suggesting.
Store fronts are an anachronism. Building new commercial property in places where you can't put a service business like a bar is pointless. And very few people want to live above a bar.