I think a challenge with trying to draw a parable with a lot of existing series is that we still don't really have an accurate picture of what the ceiling for a modern Metroid game would be, given how it's been handled so lopsidedly over the years. People are bringing up Fire Emblem now, yet that was a series that didn't even scratch the best selling Metroid game until Three Houses came along, and despite all of the hubbub about Fire Emblem having to appeal to anime fans even harder to do reach success, Three Houses broke sales records somehow without having anything comparable to Camilla plastered all over the marketing in such an aggressive fashion.
Dread being 2D may have an effect on it not attaining its highest potential ceiling, and I think it's likely it won't reach that ceiling until Prime 4 comes along. It also probably won't end up affecting the fact that the ceiling can be raised at all. The unlikeliest sales successes come along when you least expect it. If you told me 15 years ago that Luigi's Mansion, a humble experimental title that only sold a couple million, would go on to become a juggernaut selling ~10 million with its most recent entry, I'd have called you crazy, and yet here we are.
en.wikipedia.org
