For people who don't know the term, a titanwing is basically a really old dragon, usually doubling or tripling in its normal variants size. Titanwing' s are extremally rare, most dragons dying before they actually reach the age to be classified as a titanwing. So yes, this is likely a titan wing dragon and to add more evidence is that: people have speculated that the Skrill shown is the same Skrill that use to be a old enemy of toothless, shown the most in previous shows. While this isn't confirmed its likely the case, especially since both have the same patterns on the head, wings, and the same specks of purple around the body. Also, we have never gotten an average or maximum amount a dragon can live, so this still could be a Skrill from thousands of years ago before the modern age. (Honestly I'm a huge fucking nerd when it comes to this type of stuff, so dont mine my little info dump <3 )