A little late to the gif party (holidays and all), but here are my thoughts:
It's long overdue, obviously. However, I'm quite surprised that the proverbial trigger was actually pulled. I really do believe that Lou saw Pete as an almost perfect alter ego behind the bench. This makes me wonder if there was pressure from above, which would also surprise me. I've been trying hard to suss this ownership group out lately, and most arrows seem to point to "don't really care". But, something must be going on here... I do think it's fair to say that this might be the first time Lou is feeling noticeable heat from fans, the media (who are finally letting loose and having a field day with him), and maybe even ownership. It will be very interesting to see what his next moves are.
Looking at the way this came out, it does seem likely that it was leaked from the PDB side. I think the little talk Lou's going to have with the players will largely be a "keep your mouths shut" warning. I wonder if Jagr can comply?
Rumors pointing to both Oates and Martin. Oates would be horrendous, and Martin...? What's the point, really? As I've said before, I'd prefer Kowalsky, but Barr would be fine as an interim as well, and would seem to be the most likely candidate. As long as focus shifts strongly to development, I'll be happy. If it's still a "win now or die trying" vet-fest, then it will become even more obvious that larger organizational changes are in order.
tl;dr: Good start, but it's premature to feel too much optimism.