I'll give it one more try to explain this: homes aren't as far apart from one another and they're on smaller lots (a good thing IMO), plus the Memphis suburbs aren't bulbs of population/business in the middle of nowhere with super low dense housing or nothing between them.
I don't know your age, but nothing is impossible when it comes to constructing more urban housing. I'm 32 years old and for the first 25 years of my life, before I left Tennessee to find work and success out of state, I remember Nashville was a pretty terrible city. Sure, it had a nice suburban growth thing like most sunbelt cities, but the city was just awful. It seems just as I left town things began to change and a lot of urban housing began to pop up with some serious investments into parks and public amenities. The Nashville I remember was downright nasty in the late 90's and early 00's, if you stepped south of Broadway, it was all 1950's-like ran down one story block industrial/warehouse type structures straight to the highway loop. No one lived downtown, and when I say no one I mean there probably wasn't even 1,000 people in the entire inner loop area south of Jefferson Street. Even if you included Germantown/North downtown it was maybe a few hundred people more, most of whom were indigent with the city paying little attention to them. It was kind of depressing...
Things are changing in Nashville in a way I've never seen before. How does this relate to Memphis? Well you indicated you think development in Memphis is "a long shot," but again I reference my youth. In the late 90's and early 00's, in Tennessee at least, Memphis was the place to catch up to in terms of downtown residential and lifestyle options. The trolley opened in 1992, the extensions along the riverfront and Madison Ave were added later on and functioning by 2004, Harbortown had been planned and built since the early 90's, South Bluffs were booming with residences. Memphis had opened Peabody Place just after 2000, the Beale St nightlife district was alive as any could be.
We're talking about only 10 to 15 years ago Memphis was light years ahead of Nashville in the urban living department. Between South Bluffs, Harbortown, and the renos and other condo/apartment projects right in downtown the center city area had over 30,000 residents in the late 90's while Nashville had almost nothing at all, maybe a few hundred.
Never, ever say never when it comes to possibility. Just because downtown residential has slowed in Memphis doesn't mean its not going to happen. Memphis got hit harder by the global recession - for whatever reason - and hasn't bounced back quite as fast. Someday, urban housing startups will certainly expand.
And just be thankful Memphis doesn't have these absurd transit debates happening up here in Nashville, I've made my AMP feelings very clear on this and other forums.
The trolley system is going through some technical glitches, but it'll be back online soon enough. Memphis may have challenges, but there is little reason for it to not change. It will take some time, and besides it still has a higher downtown population than Nashville even with all these new condos.
Since I've got a lot of time on my hands these days, I just drove down to Memphis last week and spent an entire day roaming around downtown and midtown. Brought back memories for me, and I still get the feeling that downtown is very healthy. The most depressing thing I saw was a completely shuttered Peabody Place. But Memphis still has tons of people living in the urban core and the Main Street Mall still is charming with classic Memphis architecture.