ARS Technica reports its still a mystery whether Microsoft plans to upgrade current Windows Phone devices to Windows Phone 8:
We asked Microsoft for a comment, hoping to get something more than a ropey translation—maybe a word about when the software might be released, or what the situation would be for handsets such as the Dell Venue Pro that have been more or less abandoned by their manufacturers. But unfortunately, such a comment was not forthcoming. Instead, this is what Microsoft had to say, in a statement that is attributable only to a "Microsoft spokesman:"
We have stated publicly that all apps in our Marketplace today will run on the next version of Windows Phone. Beyond that, we have nothing to share about future releases.
We were also told that Microsoft hasn't "shared any info on [the availability of upgrades] yet." So on the one hand, we have a Microsoft employee, whose job it is to promote Microsoft technologies, talking about the updates while apparently representing Microsoft; on the other hand, we have Microsoft telling us that it hasn't actually said a word about these updates.