It will always be suitable.
... I think it's time to crisp it up a bit. It looks sort of fuzzy, like a jpg file that's been opened, saved, re-saved and tampered with so many times that the pixels start to bleed an mix. Sort of like some of the old shop items look.
I like the icon of the little mahogany haired girl. I feel like everyone wants to update everything lately and of course change is great but it's also nice to recognize the past and remember our roots. The mahogany haired girl is what made me JOIN Gaia — no it's not Gaia-tan, Gaia-tan is an evolved version of that girl — since it was the default character before modifying it according to preference. I miss the old symbolism I used to see all the time so if there's a hint of it around, I'm all for it! The only other symbol I wouldn't mind as the icon would be the obvious mini angel wing sticker.
I think the wing sticker is hardly unique. I mean, come on, a stylized kawaii desu angel wing? That's like a staple for shoujo manga.
I like the Gaia-Tan icon we have, and I would be very offended if it was forced to change. However, if we chose from a variety of icons in preferences I would be fine. Gaia-Tan is Gaia, so she's still 100% suitable for Gaia.
I'd kind of like the Gaia wing in that little box though. I think that'd be cute.
But the redheaded newbie looking chick suits me just fine. It's sort of a callback to the days of when I first joined Gaia and the 'create your avatar' for new people was a sort of... blue oval that had that girl with the peasant clothes on.