This is indeed something to consider. The same thing happened with Decred: the ticker is DCR and there was a currency on yobit, called deltacredits, that had the same ticker. In the end, decred was the stronger currency and kinda overruled deltacredits (which still had a small but active community). Obviously, this was not well received. Additionally, deltacredits volume and price spiked for a few hours, probably due to people thinking it was Decred.

Now, you could argue that Iconomi doesn't need to care about some half dead yobit listed currency. On the other hand, it may be good practice to contact IC Coin and yobit as soon as possible to find a solution. I don't necessarily mean a solution for Iconomi, I think iconomi is big enough now to simply state their intentions to use the ticker and tell the others to find a way to deal with it.