Note the quotations there. I'm not bashing any of those games, but instead asking your opinion on the subject.
For those that weren't aware, Notch has cited Infiniminer and Dwarf Fortress as being major influences on his development of Minecraft - Infiniminer for the gameplay aspects and Dwarf Fortress for the humor. Infiniminer was very similar to how Minecraft works: dig up blocks of materials and use them to build stuff.
Infiniminer folded when the source code got leaked and the developer decided he wasn't gonna spend more time on the clusterfuck it turned into. Dwarf Fortress is still going strong, last I checked. The developer of Infiniminer tacitly endorsed Minecraft; I'm sure he's jealous of all the hookers and blow Notch can buy with how many units he's shipped, but he said he was flattered by how successful his original concept (dig up stuff and then build shit with it) worked out.
This is a quick Cliff Notes paraphrasing, but it's just to set the scene.
Now, FortressCraft is a Minecraft clone for Xbox, though they've mentioned plans to bring it to the PC (where it will probably get crushed by Minecraft.) Basically, FortressCraft is Minecraft's Creative mode with some twists and differences made by the developer. Now, that in itself isn't that big of a deal - people made dozens of Diablo 2 clones and Notch himself cribbed heavily from Infiniminer. Instead, the issue is with the developer of FortressCraft, who has from what I've been able find done everything he can to avoid mentioning he basically copied Minecraft's Creative mode for his base. In fact, in one IGN interview with him, he actually attacks Minecraft (and through it, Notch), saying it's past its prime and that it will only sell on name alone. Pretty ballsy words for someone who's only sold 500,000 units to Minecraft's 3.8 million.
As near as I can tell, FortressCraft is JUST basically Minecraft's Creative mode right now - there is no Survival mode clone. It's apparently being released in "Chapters", so I'm sure there are plans for a Survival mode in the works. FortressCraft supports multiplayer.
Total Miner is the other shoe - it appears to be a Minecraft Survival mode clone with no Creative mode version. I haven't really heard anything about it, but the Youtube videos... well, it's REALLY hard not to look at it and go "oh wow you just copied Minecraft didn't you?" It must be small change, because even Wikipedia doesn't have an article on it, and Wikipedia has articles for games and anime more than anything else.
And lastly, we have Terraria, and I imagine most people are familiar with it - it's basically a sort of 2D sidescrolling Minecraft. I haven't played it and have no real interest in playing it (only sidescrollers I like are Metroidvanias, and I liked Trine, too), but word on the street is that the developers cited Minecraft as a major influence, that Notch plays it and enjoys the hell out of it, and that both parties like each other. I've heard it's a helluva lot of fun, but it just doesn't appeal to me.
So what're your opinions? Do you guys think Minecraft will be a one-off deal, where only the original is truly successful, or do you think people will be able to clone it successfully? Where do you see Minecraft and its eventual clones going?