This is indeed pretty low and considering the amount of users you will definitely have performances issues... However it should work in any case.
I would suggest going to 10.4.7 with this configuration. When you get the chance to upgrade your hardware you can go to 10.5 or 2018.1 which uses the new hyper engine.
I would avoid having to many scheduled tasks / extracts refreshes. Also avoid having too many complex viz which require computing power.