I think most points have already been addressed, however here are a few extending comments.
The longterm goal of SFML: is it meant to be used for small hobby projects or is it a serious alternative for SDL meant for creating professional 2D games?
We're not trying to be just another alternative to library X. We're not providing feature sets based on what other libraries do, instead SFML is developed while always keeping its own name in mind: Simple, Fast and Multimedia. Whether something gets added to SFML largely depends on whether it fits into the scope of SFML, whether it has real use cases and whether there is someone willing to help implement it.
What is a "
professional 2D game" and what requirements do you have for a multimedia library implementing a "
professional 2D game"? What makes SDL more "professional" than other libraries?
If all you need is a list of "professionally" created games, you may check out some of the titles listed on
Wikipedia, which by now is already missing some titles such as
Dispersio or
Remnants of Naezith or
CUIT.
A clear roadmap for the next major version of the library and hopefully a rough timetable.
There have never been time estimates and there never will be, because it's impossible to fulfill. Everyone who works on SFML is doing so voluntarily and in their free time. We can't force people to spend x-amount of hours on SFML to fulfill goal XY.
If you're interested to see what we've roughly planned for the next version, you can check the
GitHub milestones and
GitHub projects.
Additionally, we've just opened a new
sub-forum dedicated to discussions on SFML's development.
I really like SFML and would love to use it for a professional game but the uncertainty of what and when features will be added and bugs fixed makes me a little hesitant. Things like issues 1 and 7 still being open 5-6 years after reported/first discussed.
As mentioned by Hiura, the fastest way to get a feature or bugfix into SFML is by being active on your end.