It was obviously fake from the first mention of "SMB4" since the SNES SMW is the official 4.
Nintendo hasn't made any direct sequels in a Mario series since Lost Levels. Mario Land 2 played nothing like the first in the series, for example. Actually, I take that back because I am unsure if Galaxy 2 was a direct sequel to Galaxy 1 since I couldn't stand Galaxy 1 so didn't bother to even learn about 2.
Hmm. If there was a game similar to SMB3 and still in the Mario mainseries it would be neat. However I think there would be different lands compared to desert, grass, and ice. Like an area with all cave levels, dungeons or all jungle levels or all water levels and not just all half water and land levels. Maybe even all vertical levels that require going up (because down would be really easy). Maybe even all castle based levels. Some things I liked best about the game was the many different enemies/hazards, creative level designs, airships, and most of all the fights with Boom Boom and the Koopalings. There were some interesting settings like the tower that leads you to the sky and the maze of pipes in desert land, but theme wise they were very straightforward and a tad simple ideas. Most levels required going to the right to finish the level. And the hammer suit and frog suits were neat too. Those I'd like to see come back. Not sure how you can get a concept out of that other than the overworld and level/ enemy design but it is something to work with. It just doesn't sound super original.
Hmm. If there was a game similar to SMB3 and still in the Mario mainseries it would be neat. However I think there would be different lands compared to desert, grass, and ice. Like an area with all cave levels, dungeons or all jungle levels or all water levels and not just all half water and land levels. Maybe even all vertical levels that require going up (because down would be really easy). Maybe even all castle based levels. Some things I liked best about the game was the many different enemies/hazards, creative level designs, airships, and most of all the fights with Boom Boom and the Koopalings. There were some interesting settings like the tower that leads you to the sky and the maze of pipes in desert land, but theme wise they were very straightforward and a tad simple ideas. Most levels required going to the right to finish the level. And the hammer suit and frog suits were neat too. Those I'd like to see come back. Not sure how you can get a concept out of that other than the overworld and level/ enemy design but it is something to work with. It just doesn't sound super original.
I think Mario Adventure was like that. It was a pretty good (for the time) mod of SMB 3 which was basically built around taking a single 'weird' theme in every world and using it to its fullest.
But an official Nintendo game in a similar vein could be interesting, assuming it was kept as a fairly cheap eShop title rather than priced as a retail game. Kind of like the Lost Levels to some degree (and that should have been a half price game at best).