Found something encouraging on the Lothian Leisure Development website, here is an extract from their home page:

EDINBURGH INTERNATIONAL ARENA
Edinburgh is the last European capital and major UK city without a large capacity, purpose-built indoor arena.

After several years searching for a viable solution, LLD is proud to be working with Midlothian Council to provide the area with the modern indoor arena it deserves.

The development will be situated close to Edinburgh city centre at West Straiton. As well as an 8000-capacity indoor arena, it will offer conference, retail and leisure space including a cinema and two hotels.

Construction is expected to begin in 2022, with plans to open Edinburgh International Arena to the public in 2023/24.

You can find their website at: https://lothianleisure.com/development/

Cheers,

Martin