I'm hopeful that the Affinity line will be permitted to maintain one of the principle reasons for it's success—reasonably priced, non-subscription pricing. If it switches to a subscription model then there's less to distinguish it from Adobe, which has more features and is seen as 'industry standard' by many.
I can't help but reflect on some of the graphics applications I've used over the years. I started with Illustrator 1.0 and Photoshop 1.0 (which was a big step up from MacPaint, I can tell you). Aldus Freehand became my favourite raster tool but Adobe bought it and killed it. (Same thing happened to Aldus PageMaker → Adobe PageMaker → dead.) I went back to Illustrator. I'd hate to see the same thing happen for Affinity Designer but perhaps I'll be back using Illustrator again in my dotage. Such is life, apparently.
The Affinity and Canva Teams are making the right noises and likely have the best intentions but there's no way of knowing what will happen down the track. All it takes is one new CEO driven by short-sighted greed, and everything changes overnight.
I don't think there's much point worrying about it . Just carry on and stay flexible. Here in 2024 Affinity is still the best thing for my needs.