The CPU tends to be the limiting factor rather than RAM.
 Also minor edits like cutting sections out are relatively easy but if you get in to more complex stuff like color grading it takes much more grunt.
Any reasonably powerful machine under 5 years old might well cope but the time taken to render may be frustrating with longer clips.
At worst you might need to mainly stick with 1080p which is still very decent HD.

There's also the 2.7K which some think is actually the optimum setting for these sensors claiming to do 4K