I understand you are looking to switch your provider and are wondering if the Slingbox will have a remote code for your new model of cable box.
Here is an article that should help you discover the models of cable boxes that already have remote codes:
What you will want to do is select your Slingbox model then type in the next line your provider you are interested in. This tool should provide you with the cable box models that are supported.
Hope this helps!
The Sling Moderation Team - Leanne