Not my field, but ...
There used to be a lot more submarine cables and they all shared a couple of characteristics:
+ They were (still are) expensive to lay (an attribute that all cables, long and short, aerial, surface, buried and submarine, alike share);
+ They were difficult (some almost impossible) to repair;
+ Their "latency" (lack of that 1/4 second delay thing you get on satellites when your signal has to travel 75,000+ km) is very good;
+ They had a milited (20 yearish) life span; and
+ They had (relatively) low bandwidth (capacity).
Newer fibre optic cables are still expensive to lay and hard to repair if they break but they have absolutely gifuckingnormous bandwidths and they have a long(er) lifespan (35-50 years?).
Satellites have eaten into submarine cables profit margins; while they cannot replace them (bandwidth is too low), they can be a lot more flexible - locatable terminals, steerable beams, etc, and they are (relatively) cheap.