A couple of you guys keep saying that there's "no place to put it", and Majora's Cat, you kept mentioning the sand areas in replacement of it, but the sand areas are actually part of why it should have been in the game. Let me explain:
Twilight Princess actually had 6 provinces. A lot of people seem to forget about this now, for some reason. Ordona Province was dropped from Skyward Sword obviously, and they kept Faron, Eldin, and Lanayru, but there were two others: Desert Province and Peak Province.
Desert Province was located right by Lanayru (and is even reached from Lake Hylia), meaning that, at least thematically speaking, they combined Lanayru Province and Desert Province in Skyward Sword. Prior to release, I was thinking they'd combined Peak Province, too, but into Eldin Province. Think about it. Peak Province is also reached from Lanayru, but it's placed adjacent to Eldin and it's also a mountain area. What if you journeyed from Eldin Volcano to another mountain in Eldin Province, which would be Snowpeak, or at least an earlier version of it?
I agree that the Lanayru area in Skyward Sword consists of the Lanayru Province in Twilight Princess and a part of the Desert Province. This makes perfect sense, as the large emblem that towers over the Gerudo Desert in Twilight Princess is very much like the one in Skyward Sword at the edge of the Lanayru Desert. Having established that, the Lanayru area in SS must include both Lanayru Province and at least a fraction of the Gerudo Desert.
Additionally, Lake Hylia is in Lanayru Province, and it could very well be the large Sand Sea that we see in Lanayru Desert. Although Lake Floria is a feasible possibility (as the Sealed Temple Link visited time and time again was named the Temple of Hylia), it would only make sense that the lake in the Faron area is named Hylia as well, but the location of this lake in Skyward Sword doesn't correspond with the location of Lake Hylia in Twilight Princess. Now the Water Temple is in Lake Hylia in Lanayru Province, which is very close to Peak Province and the Desert Province. This could mean that the Water Temple rests
beneath the sea of sand in the Lanayru area of Skyward Sword.
Ocarina of Time's Gerudo Valley and the large expanse of sand beyond the valley is in the same location as the Gerudo Desert and SS' Lanayru area. I doubt that this arid and dry area could've been turned into some other area in later Zelda games, so I would assume that all three are one and the same. Now Axle, you mentioned that Snowpeak could be turned into a later version as part of the Eldin Volcano. While the volcano is near the top of the Skyward Sword overworld map (which is just to the right of the Snowpeak mountain range), perhaps it's really
Death Mountain?
Thinking about the Eldin Volcano logically, it resides in a fire area and is in the Eldin area. Eldin Province in Twilight Princess houses Death Mountain, which is the very same that we see in Ocarina of Time. I'm not sure if this theory has been disproved yet, but as I see it, the top-center location of Eldin Volcano in SS doesn't quite match up with the location of Peak Province in Twilight Princess (which is far off to the left). Taking into account the short period of time between Skyward Sword and Twilight Princess in the timeline, it's very difficult to believe that a fire-based section of Hyrule can be covered in snow.
I think that it's a good idea to have a pair of twin mountains, but not necessarily fire and ice. A snow mountain and a fire mountain would be very interesting, as the idea of the contrasting elements of fire and ice played out very well in the Wind Waker. However, while the concept of two mountains side-by-side is neat, in reality the fire would likely melt the ice off of the other mountain, given that the two are close enough. If the two mountains should exist side-by-side, then I would prefer them to be visited at separate times during the game, perhaps separated by a few hours of gameplay.
Overall, I still stand by my opinion that the omission of an ice dungeon wasn't such a bad idea. Sand dungeons are generally ignored, and I'm glad that Skyward Sword was able to focus more attention on these areas than in previous titles. I've also noticed in Skyward Sword that every dungeon is brightly colored and doesn't use too many cool colors. Warm and bright hues are mainly used to illustrate the world of Skyloft and Hyrule, and the inclusion of a chilly, snowy area might put a damper on the constant excitement and upbeat tempo of the game.
Although Nintendo isn't a developer that pours too much thought into creating a feasible timeline progression for the Zelda franchise, I'm sure that the reasons I have stated above would make it somewhat of a chore to incorporate a snow area into Skyward Sword, especially considering the fact that there is no major ice/snow area in Ocarina of Time.
Edit: I misunderstood the meaning of what you said, Axle, and have made changes accordingly.