Bad idea. The 2.4 GHz band is already a disaster, we don't need people hogging the full 11 channels spectrum with their dual-radio router.
2.4 GHz needs to die, quite honestly.
Yes to the first, no to the second.
What we actually need is the FCC/Government shifting the high 2.4/2.5GHz band users (or the low 2.3/2.4GHz) and then freeing up some 2.4GHz spectrum. It doesn't even have to be much. Another 20-40MHz would make a HUGE difference.
Also a lot of us are far from congested areas, live with "large spreads" and 5GHz only would SUCK. Possibly suck worse than the situation a lot of people in congested areas have with 2.4GHz.
I know, I used to live with the former (14 Wifi networks near me, 3 that sometimes had STRONGER signal strength than my own Wifi network depending on where I stood in my house, each of those were on different slices, so there was no way to have a non-overlapping network). My 2.4GHz WLAN works MUCH better now that I don't have all of that congestion near me. However...if I had to live with 5GHz only in my house, I'd probably have to move from the 2APs I have inside right now to at least 3APs...and I'd probably have to move from 1 outdoor AP to possibly 2 outdoor APs (outdoor AP covers the entire backyard right now and one of my indoor APs covers the bit of my driveway, garage and front yard where I care/need reception, but I get no usable 5GHz from inside to out).
I am in Hitsimage range here with my house. I am on 1.01 acres with a ~2,500sq-ft rancher. My problem is I have a BIG 4ft thick and around 6ft wide masonry chimney on one side of my house that divides my second living room/my kids playroom and our TV watching room and garage off from the rest of the house. If I had a centrally located AP, it would provide modest coverage there, but nothing in the garage. Its also hard to have a centrally located AP as I can't really locate one in my kitchen (back center of my house) and my main living room isn't really condusive to having an AP just sitting on my wife's buffet.
So with the AP sitting in my TV watching room/playroom/second living room...it works great for coverage in that room (where we spend a lot of time in the evenings and some during the day time) and good coverage in the garage and okay coverage on the back deck and drive way...but the bedrooms on the otherside of the house and the basement have crap coverage. So I have the router in my basement office on the opposite side of the house, which provides very good coverage for the basement and good to fine coverage in the bedrooms over it.
I then have an outdoor AP to cover my backyard, because neither indoor AP really cover the backyard, even on 2.4GHz. At best I have deck coverage that is okay...but with the outdoor AP I have excellent coverage on the deck and very good to good coverage over the rest of my backyard.
5GHz on my playroom router basically just covers the playroom, half bath there and sort of/kind of the garage and living room/kitchen. It has effectively zero coverage to the bedrooms or bathroom on the other side of the house and no coverage in the front. The basement router can do 5GHz for the whole basement, but the storage room (which is 1/4 of the basement, and includes my server rack) is at best mediocre coverage on 5GHz...and the coverage upstairs is good in my bedroom right over the router, but it is poor at best in the other two bedrooms and bath room.
Really what I'd like to see is workable DFS added to free up some more 5GHz channels for use as well as being able to add 3.6GHz, which IIRC is 40MHz of spectrum (which, I'll grant isn't amazeballs...but you know what, spectrum is spectrum and it would mean a pair of 20MHz channels or a bonded 20+20MHz channel with better penetration than 5GHz, but not quite as good as 2.4GHz).
I am very skeptical of the benefit of 802.11ah with 900MHz. I really think the only good uses for it are going to be IoT as well as a standardized method of implementing 900MHz bridges (which would be VERY welcome). 900MHz just penetrates too well for a lot of use cases as well as being very frequency constrained (IIRC it is only something like 26MHz or something like that that is usable in the US in 1, 2, 4, 8, or 20MHz wide channels).