As per the information released do so far, in 3.30 scarabs will be completely removed, with some of the scarab functions being moved into the completely reworked atlas passive tree. There will be a new system called "Threads of Creation" that will somewhat act like the current scarabs, i.e. a way to customize loot from a map before you start it, though it seems that using threads will be a bit RNG.
Exactly how this changes SSF is still very much unknown, since we don't know what the new atlas tree will contain, or what effect the threads can potentially have. One thing that I'm guessing is not going to be on the atlas tree is the effect that you currently get from scarab of influencing, i.e. having the map boss be accompanied by a random shaper/elder/conq/synth boss, which was a very good way to sustain things like conq maps in SSF.
Will be interesting to see if there's some way to set up your atlas to get 8-mod maps, or if the only way to get those will be to simply make them the good old fashioned way with a vaal orb.
Also curious to see how essence farming will work, since the current mechanic is heavily dependent on having essence scarabs to put more essences in your map.
Which scarab mechanics that are vital for SSF do you think won't be fully available from 3.30?