I don't think that the value of a game should be as linearly based on how long it takes to finish as is traditionally viewed by gamers. You never know when that one game comes out that is very short but surpasses your expectations. However, I have to admit I'm a bit surprised that the original game is somewhere in the 15 hour range.
https://howlongtobeat.com/game.php?id=10032
Assuming that most of that time is genuinely well-designed content, and not super repetitive, then that's pretty great. And I imagine they'll find a way to spruce up the gameplay so that it doesn't feel too much like a GB relic.
Not to mention, I really think we're probably going to get brand new content. Multiplayer is very likely considering that the "number of players" hasn't even be determined.
I hope the feature isn't the only new selling point, as I'm not much of a co-op multiplayer gamer. But I can't lie, with the Switch joy-con gimmick, that would be brilliant.
I also expect new content, hopefully something that is a pretty sizeable edition to the game. Not expecting too much mind you. Plus, there will probably be a hard mode that will add on new elements to consider, maybe remixed dungeons. I could see myself really getting into this one. I don't think $60 should be much of an issue if even half of these ideas are implemented. Then again, execution > concept. It's possible that this game will feel a bit too sterile for the price.