The command line will live on as long as authors and readers keep enjoying fiction made with it. But many have pointed out there is a huge market of readers (print and digital) and casual gamers who ought to love all this free IF, but sadly, they aren’t exactly flocking to it.
One reason must be the interface. Horace Torys

Horace has posted some mock-ups of text adventure games played without a traditional command-line interface. Though I love being able to write to computer games, I would probably play more on my hand-held computers if the interface didn’t require so much typing.

Here is the comment I posted on his blog:

One way to solve the keyword density problem is to start with plain
text, and several layers of hyperlinks that are visible at different
times. By that I mean perhaps the player touches a compass direction,
and all the other exit words are highlighted (but not quite as boldly as
the word you touched). Likewise, touching the name of an NPC might
cause a secondary highlight to appear on words representing topics to
ask the NPC about.

The iPhone/iPad has a gesture vocabulary
that includes touch, long touch, tap, pinch closed (could map to take”)
and pinch open (could be “drop,” but could also open a verb palette,
inventory list, or some other context-sensitive tool).

While
it’s tempting to imagine a new interface that lets you play existing
games without typing, a new interface will generate a new kind of
artwork, just as the introduction of the chorus, the proscenium arch,
spotlights, and microphones each changed the medium of theater because
playwrights and production designers fed off of each other’s
innovations.

At any rate, if you plan to use the new interface to
play existing IF games, because IF authors have made no attempt to make
visible on the screen all the words the player needs to type, and
because a list of all words that the game recognizes would be full of
spoilers, I can’t really see any way of banishing the CLI for existing
games. So the challenge is to write new works, native to the new
interface — using its constraints to help tell the story.

Perhaps
in a new interface, you could drag a word to an “i” icon to add it to
your inventory, and drag one word to another word to indicate “use word 1
on word 2”. This is far more simpler than CLI, but far more
interactive than simply clicking a link, as in literary hypertext. If
you exclude the possibility of using the CLI, then part of the gameplay
involves figuring out how to get the screen to display the two words you
want at the same time, so that you can drag one word onto the other.

Just
as the best IF authors somehow manage to write variations of “You can’t
do that” in creative ways that preserve the aesthetic experience, the
best drag-and-drop IF authors would be inspired by the constraints
inherent in the interface.

I agree with David… at some point,
the next step will be to implement a mock-up (maybe of “Cloak of
Darkness”) and see what happens.