So I have fought this for a long time (atrophy of some skills). I have held a number of Chief Software Architect, CTO and other similar roles over the years, of course I started as a jr developer way back (over 20 years ago). The skillset for these style of roles is not the same thing as being a good developer as you already know, yet without being a good developer it is hard to do those roles IMO.
My 2 cents. You will never keep your skills as sharp as they were when you were coding daily. But you must make every effort to stay current, experiment and still touch code. Personally, I like to do this in prototyping and proving architecture points with the team/client etc. This way you stay current, you are relevant and the team/client has confidence in your recommendation/guidance. You also will develop new skills which will be more important than just being a developer.
As a solutions architect you will spend most of your time helping other teams architect their solution integrating solutions your employer has developed into their systems. So it is not uncommon you will do POC work and produce some code, but it won't be production level final code generally. But in that role you'll also likely get the opportunities to write documents, white papers etc on how to architect solutions given the product(s) your employer has made. As well as integrations etc. This is how you can really stay sharp, and you will need to because you will have technical people from your clients challenging you, some of them will be extremely sharp, others not so much.
IMO the 2 most important skills as an architect (especially as a Solutions Architect), 1. Communication, 2. Delegation (e.g. don't micromanage things or set them up that way). Communication is not just in getting back to people, although that is huge, it is also communicating very technical details to people across the spectrum of competency. This can be the most challenging thing IMO.
Congrats on the new role, I am sure you will enjoy it.