Please do not stop supporting the slingbox Pro HD.
It currently doesn't support Chromecast, however it does have roku and Apple airplay support. So I am hopeful that the Pro HD has the capabilities to support Chromecast, but the folks at sling haven't had the developer resources to enable the Chromecast feature on my older sling device.
I implore the company to devote developer resources to add Chromecast support to the slingbox Pro HD.
If there are any plans to do this, please write here. Also if the company had said definitively that they are doing support with this model, then please write about it here too.