It wouldn't be offered by casino's but your Lottery could offer online gaming just like what Delaware is currently doing. Of course legislation would have to be passed for this to be allowed or the Lottery may have the power to do it, not sure.
Then when states start forming pact's with each other you'll be able to play in other licensed states.
Example: If Nevada forms a pact with N.J. at some point then if you live in Nevada you'd be able to play on the site's in N.J. and people in N.J. will be able to play on sites in Nevada.
I can see many states working together within the next two - three years.