no.  it is not possible to say with any kind of accuracy except to
generalize that the degree of myopia that would likely develop would
be quite low.  what you read is true over a large population average
and applies mostly to progressive, childhood-onset myopia.  young
children who develop myopia at about age 6-7 will usually turn out to
be high myopes.

i am an adult onset myope like the "someone" you describe in your
question.  my myopia began when I was in graduate school in my
mid-20s.  now I am about -0.75 in one eye and about -1.75 in the other
eye.  thats a lower prescription and for a person who is presbyopic
(=difficulty focusing at near associated with middle age) like me its
actually a good prescription to have.

Not with any guarantee but it's doubtful yours will go more than -2.00.

As such, it's a very nice adaptation for near work that you'll appreciate
when you're 45 or 50.

-MT

not with certainty but probably not too strong.