Exchange is unlikely to happen.
First, Microsoft's product research suggests that most computer users are satisfied with their current hosted services (including Hotmail, AOL, gMail, etc). Next, managing a mail server is a complex task, and there is only a limited amount of simplification that Microsoft could do before they would make a "Windows Home Exchange Server" pretty useless except in the most limited of circumstances. Finally, Exchange is already a core component of another Microsoft product. They are unlikely to add anything close to it to a product that costs (literally) 1/3d to 1/10th as much.
That said, you should submit product suggestions through
Connect.
I'm not on the WHS team, I just post a lot. :)