Workflow is a personal choice and you do have the option to use either path but I believe that the path forward for Topaz Labs is to migrate the plugins to be accessible from the Studio interface.
To quote Topaz Labs ...
"We're still committed to our products being used as plugins, we're a plugin company, and although studio is an editor itself as well, it's real power is as a framework or processing engine. The plan is to get out products integrated into this engine so we can speed up new feature development in the form of tools and adjustments but it will all run through the Topaz Studio framework.
That said, even though tools like Detail, Clarity and Impression are now in studio, and you can still access that work-space directly through Photoshop, under the Topaz Studio category instead of the Topaz Labs category.
We're definitely not going to force people to only edit in Studio, we want you to be able to access that toolbox where ever you want, right now we work with Photoshop and Lightroom officially. But we want to expand that to include other editors. Creativity is about options, we don't want to stifle that at all."
So, in essence the development going forward will be through Adjustments integrated in Topaz Studio but the original plugins, although they will no longer be updated, are still available via the Topaz Labs filter menu.