Yes, and we have been for a while. But as you can imagine, you can't stop adding features to your existing product and expect to survive. 1M lines of code isn't something you can port quickly.
Another thing I'd be curious about is the line at which the opportunity cost of not making the transition surpasses the cost of not developing new Flash features.
When a bank CEO, who has no idea about anything except "Well Adobe is a big company and I've never heard anything about this W3C, and how long will it take? How much will I make off it right now?" hears (if he even does) that Apple doesn't like flash, he won't care.