My understanding is that SDL provides the surface to draw on as part of the window, but not a 2D vector graphic engine on top. You've got only draw Line/Rect/pixel functions in SDL. To render a svg/png/jpeg that you want for games on the SDL surface, the normal way is to use a third party library such as Cairo.

For 3D I believe people use SDL combined with open GL or direct3D instead of Cairo but I don't know the details.

For events (keyboard, mouse, joypad) I use SDL event management and it works differently on each OS. I wrote in the readMe the different set-ups to make it work on each OS. On Windows and Linux I can use the latest Pharo. On Mac I use old Pharo 5 images.

I guess it's possible to use SDL for audio, but it seems there is no code relative to audio in the SDL binding and in OSWindow in Pharo. That's why I did not go that way. I tried multiple things but I successfully run audio code in Pharo only with the openAL binding and .wav file (and even in this case, I had to install external librairies in Mac OS...).

Whichever if Cairo stays around or not does not really matter, normally one uses Cairo through Athens or Sparta, abstraction layers on top of 2D graphic engines. I've worked with other 2D engines and the API are always almost the same, so I have no doubt that if Cairo support is dropped we can re-bind Athens/Sparta with another 2D engine (such as engines used by web browsers).