I dunno, that sounds like a bad idea because it relies on said internet connection.
A unified x86_32 and x86_64 Live image is unlikely though, given that any efforts to make this possible have been scorned because of two things: saying that packages solve the arch problem (because any changes to make this possible would affect everything), and that anything that would offer this capability is more useful to proprietary software than open source software.
Personally, I don't agree with either argument. The first argument about package managers is somewhat true, but at the same time, not true. Packages do make it easier to handle arch-specific dependencies, and generally arch-independent data is split out into a separate package that is pulled during installation, but the initial point of entry for either arch requires KNOWING that your system actually uses either arch. While it is true most systems sold today are x86_64 capable, it isn't true that most systems in USE are x86_64 capable.
As far as the installable media goes, I don't really see too much of a reason to fuse the x86_32 and x86_64 stuff together, because frankly, the people that are installing through traditional media have to know what they are doing anyway, since you have to know what you are doing to be able to select all those packages and stuff.
The Live images though, are intended not only for demonstration, but for easy installation. In this case, I could see fusing the two arches together.
As for the second argument, open source software typically do not need to offer binaries, since source is available. However, being able to offer binaries that will work on a wide variety of UNIX platforms would be wonderful, and also it would be easier to support, since the binaries are configured in a specific way. As it currently works, it isn't a good idea to bring issues you have with distro packages of software to the actual maker of the software, because there are too many variables to help predict the issue, mainly because each distribution configures packages differently for package generation. Having a single set of binaries that can be offered for a multitude of platforms that anyone can download makes it easier on upstream to handle cases.
However, I will grant that it makes life for proprietary software makers a lot easier. Since there are lots of haters to those makers here and in other distributions, it is unlikely you will see any solution like this in a distribution unless they want to get flamed out of existence.