There are some remaining issues that should be fixed before the 18.05 release, but aren't receiving much attention:

init requires double quotas when running under sequence #2755 (init should request quota upgrades when needed)
nit_fb: add optional transparency #2728 (less important, but just needs to be merged)
Framebuffer has_alpha() function #2723
Noux: rmdir dir/ (trailing slash) does not work #2686
Multiple rump-backed file-systems not supported by VFS library #2681
Additional pixel format support #2045 (important for a library i'm writing; just needs to be merged)

All of these should be fairly easy fixes, and at least 2 already have patches that just need to be merged.