Concrete normally more durable when there are less amount of voids in it.
Normal concrete can have the voids in it which may lead to lower durability compare to SCC
SCC do have use of high cementicious content in it which makes concrete to keep gaining strength in later stages and actually make it even more stronger as it ages.
Self compacting concrete SCC itself means, it compact itself to ensure no voids in it, if mix design is done well to ensure there are no voids and all in aggregate grading meets the relevant standard specifications or the user specific specification some one arrived after doing lot of trial. that concrete will have less voids, impermeable and high amount of cementicious - this definitely will help to increase the durability of the concrete.
SCC will be more durable product as compare with NCC.
If you search on internet, you will find the mix opinion of various peoples on this subject, so its matter of research and waiting for another few decades to observed the durability of structures made with modern SCC design which will prove either, they are best durable than NCC or worst than NCC.