What will happen if the Edo-Tensei user dies? What will happen to the reincarnated people if the Edo-Tensei user (jutsu caster) dies?

As Kabuto mentioned, the jutsu will not be released if he gets killed. If that's the case, what will happen to the reincarnated shinobi?
If the summoner dies, then all the reanimated shinobi will keep on existing without the controller.

Before I begin, it is important to know how control works in Edo Tensei.
There are 3 methods of control the summoner can place on a shinobi:


Shinobi are allowed to have control over themselves 
Shinobi are given an objective and they must complete it
Summoner fully controls the Shinobi


Kabuto can decide which layer of control he wants to assert on each individual. 

When alive, Kabuto can freely change the control type over all the shinobi under his command. Once he is dead, his army will continue fulfilling his last order before he passed. 

That means people who had control over themselves still have control of themselves. Ones that are given some assignment(s) still have to finish that assignment(s) (which is probably a combination of very detailed tasks in order to gain leverage over Madara). As for the last group, they revert back to the most recent option between 1 and 2. If they were previously had full control, then they will regain full again.

NOTE: While Kabuto determines his control over his army, there are multiple ways to also break out of it - explained in my answer here.