I recently read an article over at Between the Staples regarding the future of comics and the switch to digital media. Personally, I don’t see digital comics taking the place of printed comics. For me, I see comic fans for the most part needing something physical to collect. I don’t think a download can give them the same satisfaction as that rare find. Sure, I think digital comics have a place and I think they can co-exist with their printed brothers. For starters, they are a great for the casual fan who doesn’t have the collector mentality. If you just want to try something new and don’t care about the collectability, then digital comics could work for you. But I see if being a greater alternative to the closet fan who is given grief by their girlfriend for still collecting comics. Gone are the days of arguments over you comics taking up too much space int the house/apartment. Arguments about your comics taking up too much space on your hard drive are another story though. 
The article is a good read and can be checked out here: http://betweenthestaples.com/2009/10/28/the-future-of-comics/