To be had

To be had
 

This idiom has two meanings, but I dont understand the meaning in the following sentence.
There is a great career to be had in retaurant service.
What does it mean?

Here the phrasing is an indirect way of saying that a career in restaurant service will be/would make a great career, especially if one takes advantage of it.

There is fun to be had. = There will be fun. = It will be fun (if one does whatever is being presented).

-also-

Fun will be had (is to be had) by all. = All will have fun. = Todos se divertirán.

Is it a periphrasis with future meaning?

No, it's just a set phrase, and it has other meanings than that of a future event.

What what is to be had is not a person, to be had can mean:
will be/would be, will be found, can be found, is found, will have, is held

This phrasing is seen in advertising more than anywhere else.

Ant the other two meanings:
Outwit sb
And have sex with sb
Are ther still valid nowadays?