Your are most likely referring to Amazon's "Pop Up Stores" (the most active of Amazon's expansion models). These are literally Kiosk type stores located in malls and other tactical locations such as college campuses. Not the same thing we're doing.
Amazon is horizontally integrating, but nothing near to the scale or similar to what we are doing. Theirs is one of acquisition of businesses to expand (Whole Foods).
Target is using demographics to position new stores in areas which current and future guest are found. If I recall correctly, Target's key demographic market is women, ages 20 - 40 years of age, either going to college, attended college, or graduated from college, anticipates having a family or has a family. This is why the push into urban areas and college campuses.
Eventually this base does move on and out of those areas. Hopefully their experience builds loyalty and they continue to shop at the traditional stores.
The above being said, Target is building brick and mortar operations in expensive areas to operate a retail business in. The smaller the foot print, the higher $/sq ft required. You can't get around that cost impacting the profitability of such stores. Some stores will stay open, but a lot will close due to the bottom line.
All of the above business models you mention have been done before. The results were the same over time, they closed. They just couldn't generate enough $/sq. ft. Unless Target is willing to heavily subsidize these stores, or lower the profitability expectations, the inevitable will happen. You can't reinvent the wheel.
Amazon, unlike us, has the advantage of selling product where the $/sq ft is substantially less. We on the other hand have the advantage of having a place where you can go and actually touch the product. We just have to make sure we have merchandise when the guest arrive or they'll go elsewhere.