There are a couple of reasons why I say that, and they are kinda interlinked.
For starters - there were those reports around the web of an HP presentation that had Intel and NVIDIA for Intel EM64T platform. When EM64T comes around, its very likely to require a new bus license; NVIDIA also has plenty of experience with AMD's 64-bit platform and Intel may look to leverage some of that with their 64-bit desktop platform. Given NVIDIA always likes to aim for the high end, its unlikely that they would want to create an Intel chipset without SoundStorm given that Intel already have some encode capabilities (having it at lower CPU utilisation, because theirs is fully hardware based, than Intel would also be a selling point for NVIDIA).
Now, the other issue they have presently is that they are only working on the AMD market at the moment. This has led them down the path of having a single chip chipset controller, which offers benefits for that single platform, but also means you areless likely to want to waste silicon on areas that may only be utilised on a small percentage of the platforms available; a single chip also means more time if you want to offer different options. You'll note that no other chipset vendor has followed NVIDIA's route yet, and thats down to one simple reason - all the other are presently dealing with both Intel and AMD markets and they get to leverage their "Media Communications Processors" (Southbridges) across two different platforms - this spreads the risk and also enables them to have more options by mixing and matching the Northbridges to various southbridge options on both platforms.
Should NVIDIA enter the Intel market then its likely that they will go back to making a two chip chipset, and it wouldn't surprise me if they did that for the AMD platform again. If this were the case the work put in can the be spread across both platforms and making a number of Southbridge options (some with SoundStorm, some without) dependant on the costs and targets for the vendor wants to aim the platform at.