I do agree that the "the future" sounds like someone totally different than the "we have plans for you".
So, either way, it means that there is someone else other than Norman. Now I am wondering if that shot of Harry is from the Electro amping process and not him watching the fedora guy come down the elevator. If so, it is possible that there are two scenes with two different guys.
Scene one would be where/when Harry is transformed into the Goblin. This could be around the time he asks "what is all of this?", and the Engineer helping him (Otto? or Smythe) replies "the future" (sounds almost like a German accent) and then there could still be a mid or post credits scene with TMITS coming down the elevator, opening the chamber doors, walking past all of the cool Sinister Six stuff and then saying (maybe while looking at a video of Peter) the "we have plans for you, Peter Parker" dialog. This would be in keeping with this idea of the man in the shadows, who will become more important in the third film. Michael Massee would ultimately be listed in the credits, once again, as Man in the shadows.
Hmm.........