I don't think the tuners would have to change. Right now, to tune a single video channel the tuners are looking at a subset of the whole SWM channel that contains a full transponder's worth of data that is on the channel. If the SWM instead sent only half of the transponder's bandwidth down each SWM channel the tuner would simply do what it normally does when the video channel of interest is on the lower half of a 102 Mhz wide SWM channel today. As VOS pointed out in an earlier post, the SWM is simply translating a wide range of RF signals into a fixed range of RF that the existing tuners are already capable of being tuned to. As long as SWM technology does not require the full transponder's worth of data to be available at the tuner input for single channel tuning to work right, putting more channels on the SWM line (with less data on each channel) would only require a software update to the current SWM capable receivers.
This assumes that the transmission/receiving method that is being used could still work even if a tuner can't "see" a whole transponder's worth of data at one time... and maybe that's a bad assumption.
Using 70 MHz bandwidth "and" the non existant SWM 11 range, gives 16 + guide, and handles the 65 MHz Spaceway Transponder.
"The key" is if the SWM chip maker has a "new and improved" chip they're working on.
The receiver "SWM screen" already has "n/a" slots, and the same [receiver] software works with the old SWM5 and SWM8, which would [again] seem to point to the SWM being the one telling the receiver "what it has and where to tune".
2.3 MHz "comm"
974 MHz guide data.
1076 MHz "and up" for 16 SWM channels [with the receiver topping out at 2156 MHz] following the 70 MHz, 2 MHz, 70 MHz spacing.