Elderly or the elderly & the number of

Dear teachers,

I read a sentence from an article as follows:

In Korea, the main workers of society between the ages of 20 through 40 will be rapidly declining while the number of elderly above 60 will surge all at the same time.

I think the sentence should be edited as follows:

In Korea, the (number of) main workers of society between the ages of 20 through 40 will be rapidly declining while the number of (the) elderly above 60 will surge all at the same time.

Is this correct?

Thanks and best regards,

David Kim