Firstly, I love what Valve have been doing with new hero designs recently.
For the longest time, Legion Commander was the only female Strength hero in the game. And even then, the hero was male in the original Dota mod and had a gender swap when ported to Dota 2.
Couple of the Strength heroes have ambiguous gender i.e. IO and Phoenix. But the rest are all male. Until more recently when Snapfire and Dawnbreaker were added to the game. Their additions were also quite unique when they came out.
Now, Legion Commander generally fits the offlane role. Snapfire fits the offlane/support role. Dawnbreaker fits the offlane/mid role.
Watch the intro trailer and look at this text in the official blog post.
My prediction is that Marci will be a melee, carry strength hero.
Judging from what we've seen in the anime and the intro trailer, she punches and karate chops people. She looks like she'll primarily have physical damage output.
Now, it's hard to guess exactly what her spells could be, but I'm fairly confident on the rest.
As an added note, I love the way heroes are designed in Dota 2. Yeah, most Agility heroes are carries, but heroes like Vengeful Spirit, Bounty Hunter, and more recently Hoodwink, are played as supports. Pangolier was a fairly rare addition as an Agility offlaner.
Most Strength heroes are offlaners, but there are several support heroes like IO, Treant Protector, Spirit Breaker, Clockwerk, Earth Spirit etc. etc.
Same goes with Intelligence heroes, even more so than the above two. And on top of that, so many heroes in the game can be played in more than one role. I just love that!
Source: https://www.reddit.com/r/DotA2/comments/q9i3i3/prediction_about_which_type_of_a_hero_marci_will/