TS3 isn't the only launcher type game which uses IE technology. I belong to several 'game clubs' which also require IE technology to manage and launch their games both on and offline. When moving forward, I would think it to be irresponsible for Microsoft not to provide some type of bridge for existing legacy applications to continue to be able to function on (for a while at least).
According to Microsoft's information concerning 'Edge', they have already stated Edge has IE mode built into it.
"Not only is Microsoft Edge a faster, more secure and more modern browsing experience than Internet Explorer, but it is also able to address a key concern: compatibility for older, legacy websites and applications. Microsoft Edge has Internet Explorer mode (“IE mode”) built in, so you can access those legacy Internet Explorer-based websites and applications straight from Microsoft Edge."
At least one responder here says they use Edge with no issue.
