Agents Of S.H.I.E.L.D. is go for a half-length sixth season. Having run three and then two mini-seasons in the last two years, they can do this.
The bigger issue may be fallout from Avengers: Infinity War...
And Coulson will be getting a boost when he appears in the (at least partially) 1990s set Captain Marvel.
And now a joke.
Coming back for half a season? I blame Thanos!