Having an A-class and a B-class is practically like having 2 cars which offers almost the same qualities, the B-class is only larger. The B-class has proven itself as a success so I do understand why they are speculating about dropping the A-class.

Aside of youngsters the A-class and B-class is also populair among people with physical problems like elder people and people with certain disabilities. Both cars has easy entries which is a great plus and criteria for choosing the A-class or B-class.
Dropping the A-class could possibly raise the bar that much that it's out of reach for some people due its higher price. Almost €4000,- difference in my country between an A150 and B150 which is quite alot of money in this carsegment.

I think it'd be better if they produced two versions of the B-class to make it more affordable for some people.
Like a short and long version or 2 doors and 4 doors version of the B-class etc.
Kind of similar to the BMW 1 series, Audi A3/sporback and Renault Scenic.