First-Gen WP7 Device Updates

Now that pretty much all of the first generation Windows Phones have mango, my question is, will there be further updates to these devices? Or will the future updates be locked only to the second generation of phones that have released this year?

I hope Windows Phone can follow the iPhone model of updates, where previous generation gets OS updates until it is two generations behind. This would really be the icing on the cake. What do you think?