I'll only speak to where Procreate shines, since I can't divulge much about Gemini. One strong area are it's smart gesture control. So things like Clipping masks, alpha masks (painting within pixels on the layer), or things like shape assistance (so long hold to make straight lines, circles, squares, etc). Other strengths I think Procreate has are things like the drawing assist (symmetry), the grids, and things like reference layers.
I think on the tools end, Procreate will still be a foundational part of many artists workflow. However, I don't think it's likely that Procreate will be able to match up to the brush engine that Adobe has in Photoshop & Gemini. The performance is incredible, and the live brushes are something else all together (the way they blend colors, bleed, etc).
I can see people using Gemini to make things closer to "traditional art", where as Procreate will still be a strong staple for things like comic illustration, where strong accurate lines are required.
Edit: I'm intentionally not speaking about Gemini too much because I can't, but I'll share some examples of the blending & art brushes a bit later so you can see what I'm talking about (we're allowed to share art, just not discuss UI or features because obviously all of that is still underdevelopment and being implemented, so it's not really a good idea to talk about things that are missing that aren't in Gemini, because they very well may be implemented upon initial / future release).