That's a great question. I wish I had an answer for you. I've been fascinated with text adventure games / interactive fiction for decades, but I haven't really been playing much lately. As such, I haven't spent much time thinking about what a "more modern" text game would look like.

At first blush, my instinct is to say that it wouldn't look much different from any reasonably contemporary MUD. I mean, "text is text" on one hand. But when you consider all the advances in tech since the origin of those text games, it's hard to imagine that there aren't some really cool new things that could be woven in.

At the very least, thanks for asking the question. Maybe it will spark an interesting idea for somebody here, and indirectly lead to the rise of the Next Great Text Adventure.