Data warehousing, Business Intelligence, Data Mining etc are considered highly specialized skills. If you are serious about moving into that area, I would not bank on interest and basic skills as the ticket there. If you really want to be successful in data mining, you should probably consider a degree in CIS or a degree in Data mining - Colorado State University has an online degree, I believe.

Sticking with ASP.Net is your best bet if you don't have the time or resources to invest in going back to school. With asp.net, you can grow your skills and profile with each project you work on while still earning a pretty good salary.