Actually I don't really see - the MEG as a coastal species.
Think about Juvie Great Whites tend to prefer waters that are between 20-1,000 ft (6-300 meters) . Adult Great Whites(15-20 footers) - seem to prefer waters between 65 -3,280 ft (20-1,000 meters)
Given the size of modern realistic size estimates for MEG(of about 40-50 ft), it was almost certain a Pelagic species.
Like most of similar size Fish(i.e. Whale Shark) or Marine mammals (Humpback & Gray Whales), the Meg would likely stay in waters that are hundreds to over 10,000 ft.
Sure.
So here's a little speculation.
If we look at it logically - the open ocean already supports several species that are the approximate size of the MEG, or larger. Including several species of Whales, & at least 2 species of sharks that similar in size(the Whale & Basking).
So logically, one would say that the oceans could easily still support the MEG.
But "if" (and I don't Believe it is), MEG still exists - then it is incredibly rare. Even rarer than species of Great Whales like the Humpback, or California Gray
which have populations numbering in the low 10,000 range. It would much rarer than the Great White -which may have a population range in the 10's of thousands world wide.
Surely if MEG still existed - it would have a population of about 1% of the Great White's - which means at best a few hundred individuals.
Which is one reason I highly doubt that it presently exists.