I agree with your intrepretation of the ending.I liked House's sacrifice a lot. I also liked the look on Forman's face when he finds House's ID tag under the table leg. Forman gives a knowing look, that he suspects House is still alive.
I have issues with how they got to that point. First, why all the drug induced ghosts? Great drama, but not part of the plot at all as House has obviously planned to fake his death all along, with the switching of dental records on the dead body, which had to be done before the fire. This reduced the retrospectives to meerly an empty plot device (one they had used before) to get old regulars back for one last cameo. I felt cheated that the situation wasn't real. He had to stay in the burning building at the window until someone saw him then split.
Did not see who the body was, but if House procured a live dying donor, he was at the least an accessory to death, or abuse of a corpse.
I got the impression that him faking his death was not something preplanned. The reason that House's ID was found in Foreman's office was because House went back to the hospital after the fire and made the swap then. That would make everything fit in line.