Currently Windows RT devices are not supported for upgrade to Windows 10. Additionally I tried upgrading my Toshiba Encore 2 to 10, but it fails in the final reboot and nicely rolls back to Windows 8.1.
So, how can I find out if my touch device can be upgraded to Windows 10?
The bottom line: The current Windows 10 Technical Preview is still in the very early stages. Do not expect it to work perfectly; indeed, expect it to break. You should not be installing it on any device for purposes other than testing. Until it becomes more stable (usually Consumer Preview or even final release), there are no guarantees your hardware will work on it. Of course, if you wish to test then you can help by reporting bugs to Microsoft or your hardware's manufacturers.
As you've noted, Windows 10 is currently not available for RT devices. However, this has nothing to do with them being touch-focused. Windows 10 Technical Preview is not available for RT because RT devices run on ARM, a different type of CPU from the x86 you see on desktop and laptop computers (and many Windows tablets, like your Encore 2).
Now, as a general rule, Windows 10 should work fine on any device with a touchscreen that worked on Windows 8.1. However, do note that this is currently a technical preview, quite early in development. Bugs are to be expected. Most bugs are likely to be in drivers, possibly including your touchscreen drivers.
The only way to be certain if your touchscreen will work on the Windows 10 Technical Preview is to either try it yourself or ask someone else with the same device. Even then, as the OS is updated (and it constantly will, during this period), it might fix bugs or introduce new bugs with your hardware.
Actually, at this point you haven't even determined that the failure to install is related to the touchscreen at all. There may be other quirks in your previous installation that prevent a successful update, or maybe Windows 10 is just not yet compatible with the current drivers you have installed. You can try to isolate the actual cause by looking at installation logs and dumps, and you can help developers fix these issues by reporting them (with more information) to Microsoft and your hardware manufacturers.
