I doubt it and I don't understand why anyone would believe so. Like many of you I've been playing with Ness for over a decade and a lot of his weaknesses still remain:
-Poor tilts
-Poor approach options since a good player will adapt to PKT2
-Bad range
-Gimmick recovery
-REALLY hard counters
-Gets outcamped easily by better projectiles forcing him to be aggressive (see point 2)
Project M gave Ness players a godsend by having PK Fire activate on shields. I was foolishly hoping SSB4 would give us that as well. With all that being said I believe Ness will be solidly placed in the Mid-Tiers.
I was under this impression too for a while, until you realize that the global changes to the game heavily alleviated a lot of those issues, in addition to a few straight up buffs.
Having poor tilts isn't really a flaw in a character. Most characters have moves they will use less, those just happen to be mapped to Ness' tilts. He makes up for it by having the best grab game out of just about everyone, and amazing aerials to boot.
As for approach, I think that Ness' approach still isn't that good, but a few other characters had their approaches gutted too, like Falco and Marth.
Bad range is a big thing that got helped in this game. Ness may still have mediocre range, but a LOT of ranged characters were screwed over. Sword characters in particular. What also helps is that these sword characters were problem matchups before, and are much more manageable now.
Gimmick recovery was buffed, by a lot. Ness can wallbounce recover now and his PKT pierces early on.
Ness has no really REALLY hard counters in this game from what I've felt so far. Worst IMO is probably Sonic.
Projectile camping may be an issue still as well, but so far, I don't think any projectile heavy characters are placing particularly well in torunaments. If they're not too frequent, then it'll hurt Ness' tier placement less.