I don't think the Tifosi will go after Leclerc straight away unless he's clearly at fault for some errors. Vettel's firmly in the firing line after his 2018 and subsequent admissions after the season.
Honda's really interesting. Ever since their re-entry into the sport they've had to play catch up, and it is the same for 2019. Except that everyone normally forgets that the frontrunners of Mercedes and Ferrari will have been doing more than a little development of their own and are expected to move ahead again. I'm just not sure that Honda have that ability to accelerate and advance their progress essentially twice as quickly as the others, who are developing through proven trusted and mature processes. Then again, that Red Bull chassis and aero package has been amazing towards the end of the season, especially in the hands of Verstappen. Perhaps Honda don't need to catch up, just close the gap enough.
The most interesting one for me is Renault. They half-lost Red Bull before, and now they're fully gone. The reputation is now sitting firmly on their works team and a McLaren that's so underperforming it is akin to someone spray painting a Williams orange. They need to take some huge steps forward if they're to break into the top six, let alone compete at that level.
Part of me really, really wants Sauber to find that magic aero loophole and 'do a Brawn'.