Unless Apple removes all software from the shelf and put it online, there will be a need for the ODD.
We know that Apple has the best servers in the world that can handle ALL the downloads when they have something new that comes out and the world wants it at the same time!Think back when Lion came out, when a new iOS comes out, what issues have you run into trying to download.
I'm a huge proponent of the optical drive, but I disagree. Its best use IMO is for backing up data to DVD's. A ten cent piece of plastic that holds 5GB.
When the trial of Adobe CS6 came out, they had no issues whatsoever delivering it as a download. Id be surprised if that couldn't happen for just about any software. Also, you install software once when you get the computer and then only very infrequently; if thats the only thing you use it for then it wouldn't be much hassle pulling out your optical drive when you had to install something.