As hard as it may be to hear that Flash is dying, it is. If I didn't use xat, I'd think twice about even having Adobe Flash Player installed at all. I didn't mean to imply that it's just going to disappear one day, because that is far from the truth. It is dying a slow and painful death for a reason; too many services still use Flash, including xat.
July 14, 2015: Firefox blocks Flash, and Facebook calls for its death
September 1, 2015: Google Chrome will start blocking Adobe Flash ads today
May 13, 2016: Google Devs Planning Flash's Demise with New "HTML5 by Default" Chrome Setting
What does this even mean? It lacks volume controls? I'd like to refrain from being rude, but I'm willing to bet neither of us have a clue about how powerful HTML5 is. It says a lot that Google feels HTML5 is mature enough to disable it on all websites, and instead force it to have to be manually activated on individual websites. They wouldn't do that unless they felt HTML5 was mature enough.
I didn't mean for this to turn into a debate about HTML5 on xat, but take my word when I say you shouldn't be expecting any interface design changes until mobile is done, and by that time, an HTML5 chat will already be on the table, presumably.