Yes, that "passenger w/o laptop" notion is a problem. I don't think that it'll be as much of a problem as you think because:
1) There are internet appliances (or will be, by the time I get to run an airline) that I can cheaply purchase for inflight surfing. The Vadem Clio
costs $999, about as much as a portable DVD player. I think that $1,000 is a lot cheaper than the cost per seat of a PTV system, as a matter of fact. If we could add Ethernet cards to it so it can attach to the Connexion system, passengers could download their files from a web-based harddrive and work (of course, on only Microsoft programs) ; then upload them once the flight is complete. The CLIO has no moving parts and is unlikely to be damaged by kids as much as a full-fledged laptop is, since laptops have spinning hard drives and fans.
Corollary: Getting people to actually use their laptops on my planes will be difficult. We'd have only web-based reservation systems (or charge money for phone service) so we could e-mail the passengers instructions on how to proceed with being connected in flight. Also we'd give out installation CDs prior to takeoff.
2) My ticket prices are a tad bit higher than usual. That gets rid of certain passengers who would be less likely to carry laptops aboard. I would bet that this also eliminates the passengers who would shop for the cheapest ticket price. In my experience, slightly higher ticket prices filter out the riffraff on airplanes. Note that on my last three Northwest flights (where, as per family directive, I shopped for price rather than service) there was a noticeablely larger fraction of passengers who caused problems like fighting and having the Port Authority police come, needed services such as wheelchairs (on flights to MNL) that cost NWA money to provide, and brought along lots of kids who have a habit for destruction. Fortunately, all of this is eliminated if you make the ticket price higher.