I was on Fandango where you can already buy tickets for Thor: Ragnarok, and the length of the film there is stated as 2 hours 10 minutes (see my screen capture attached). That would seem to contradict the much shorter running time released earlier.
Also, this Taika Waititi interview with Screen Rant might alleviate some concerns with the third film and the Hulk upstaging Thor. He states, "Personally I feel like... if the movie’s called Thor, then Thor should be the best character."
...Waititi "joked" about the post credit scene taking up much of the added minutes. I have a feeling that the post-credit scene/s for Thor Ragnarok would be the longest so far in the MCU...or in any movie in history. They will set up Infinity War and how Thor ended up floating unconscious in space.
About Thor being the best character in his movie...I am hoping that is the case. However, it all depends on the director's idea of what is a "good" character. A few months ago he delighted in comparing Thor to the lovable loser hero in Big Trouble in Little China movie. For all we know, the director thinks that is a good character. It may be good for Kurt Russel, but not to Thor.
As for the possibility of the Hulk to upstage Thor...I find it more than likely, given that the director himself stated that the Hulk will be the breakout star in the movie.