If Desktop PCs phase out, would there always be a computer on which a music software writing program could be used, such as Sibelius?
I was thinking if Desktop PCs were going to be phased out then they would mostly be replaced by laptops
They are already kinda getting phased out anyway. Apple does have a lot to do with it (look at the Mac Pro, no not the MacBook Pro, but the Mac Pro, hasn't been updated for years and unlikely to do ever again), also the rise of smartphones and tablets have made people less rely on laptops, let alone desktops.
Heya and welcome here.
I will be moving your topic in the music section.
I don't think PC-based platforms will phase out, maybe desktops PC will be completely replaced with laptops, but Windows will always remain around, so you should be fine with the current software you use. I believe Sibelius is for Windows, right? I cannot load the main site for some reasons.
Sibelius is for Windows, and Finale (another music composing software which my school uses) is also for Windows.
Also interesting you say that Sibelius.com doesn't load up. Well I tried Opera
and got this message:
Works fine in chrome though. I wonder what makes it not renderable in Opera?