As of now, Tableau Reader is still in beta for 2018.2, so it doesn't seem like Tableau has any plans (yet!) of stopping Reader usage. But from the new license types, I believe they've made it a lot cheaper to use Tableau Server at scale. As for sharing workbooks outside the company, I believe this is where either the Guest user within Tableau Server or the embedded license type would come into play.
Hope this helps!
when we share workbook to users then they can view in tableau reader. but if they have tableau Desktop then can see our data.
Please get core based server license and use guest access for other users.
BI, Aspire Systems (India) Pvt Ltd