Regarding data rates and what a standard is "supposed to be", note that standards often include future-looking or optional features that never get implemented, at least not widely implemented.
For example, 802.11n provided for up to 600 megabits/sec signaling rates, by using 4 spatial streams (4 separate transmit/receive radios, all transmitting separate parts of the data stream) but no Wi-Fi chipset vendor as far as I know has ever managed to create a commercially viable 802.11n chipset capable of 4 spatial streams. When draft-N products first came out in late 2006, they did 2 spatial streams, for 300 megabit/sec signaling. Then cheap N-in-name-only gear came out that only did 1 spatial stream for 150 megabit/sec signaling. Then around late 2009, 3 spatial stream gear came out for 450 megabit/sec signaling. But it seems like almost no one really uses 450 megabit/sec 802.11n gear.
802.11ac actually defines how to use channels up to 160MHz wide with up to 8 spatial streams for up to about 7 (technically 6.9333) gigabits/sec operation (see IEEE 802.11ac Draft 3, Table 22-61, bottom-right corner). But at first, everyone is doing 80MHz-wide channels with 3 special streams for 1.3 gigabit/sec operation. And just like we never saw 600mbps N, I doubt we'll see the ~7 gbps data rate with 11ac. We'll have moved on to a later-generation spec before then, just like we moved on from N to AC before we maxed out N.
802.11n was "supposed to be" new higher rates than we got with 802.11a and 802.11g (which both maxed out at 54mbps), by using:
- MIMO (multiple spatial streams)
- Faster modulation schemes per stream
- Wider, 40MHz channels (instead of 20MHz like a/b/g)
...And a handful of other enhancements (frame aggregation, LDPC, STBC, etc)
We saw all of those things, even though we never saw the 600mbps data rate.
802.11ac is "supposed to be" new higher rates than we got with 802.11n, by using:
- Even wider channels (80 and 160MHz)
- Even more spatial streams
- Even faster modulation schemes per stream (256 QAM)
...And another handful of other enhancements (even more frame aggregation, explicit beamforming, etc.)
I think we'll see most of those things, even if we never see the ~7 gbps rate.
And once again, some vendors will find ways to claim their stuff is AC even though it doesn't use the best parts of AC, just like vendors today say things are N even when they don't get anywhere near the 300 megabit/sec signaling rate that the very earliest N gear got.
One fun thing about this first generation of 802.11ac is that the 1.3 gbps signaling rate plus the reduced overhead thanks to more aggressive frame aggregation, means it's possible to get throughputs on Wi-Fi that beat Gigabit Ethernet. You may have to be right next to the AP to do it, but it's still interesting that since 10GigE hasn't caught on as standard equipment in PCs and laptops, it means that as 802.11ac starts to get into PCs and laptops, those devices will actually be faster over wireless than over wired networking. In some limited situations. Maybe. But still.