Yes you can keep using the Avia Layout Architect when you update to 5.0 and activate classic editor.
Little bug report on this:
I have WP 5.0 With Gutenberg Enfold 4.5.1
I noticed when I edit an icon block in the Enfold pagebuilder the editor shows up, but all text is white and code is shown, when you click on the code button, you can see the text correct.
When I install and activate the classic editor it works perfect. Hope this helps.