The consequence will be alot of people will continue to use non-ipad optimized apps on their ipad just to save money. Which will create a less than ideal user interface most likely, although that's a persons choice.
I have a different prediction. People buy new iPhone apps all the time. I mean, ALL the time. When they get an iPad, they'll start spending this money on shiny new iPad apps. Did you say you'd spent $80 on iPhone apps? Well, in a few months, even without the iPad, you'd have spent another $80 on
new iPhone apps. Now you'll probably buy iPad apps instead. Or both.
Most people who own both devices will end up with two different app collections. For the most part, they'll be separate collections -- e.g. games you play on the phone and games you play on the Pad. But there will be two categories of overlap:
• iPhone apps that work well and look pretty good on the iPad, but aren't worth spending extra money on.
• iPhone apps that you like SO much, or use so regularly, that you'll just shell out the extra bucks for an iPad version.
It's not like we're talking about huge sums of money. Maybe people who are used to getting apps for .99 or 2.99 or -- take a deep breath -- 5.99 don't remember when apps for "real" computers cost forty or fifty bucks or more. This is probably why I've got 8 screens worth of apps most of which I never even look at. Most of them cost less than a coffee at Starbucks.