Microsoft announce that Power BI Premium per User will become generally available on 2 April, 2021.
There will be a standalone licence costing $20 per user per month, or an Add-on for users already licensed with a Power BI Pro or Office 365/Microsoft 365 E5 licence costing $10 per user per month.
Find the announcement article, which also details Power BI Premium features and capabilities, here: http://bit.ly/3rm1B4E, and a useful FAQ on the Power BI Premium per User licence here: https://bit.ly/3j1YNWc.