Too vague. You might be able to get a positive ROI at some point during those 6 months if you actually sell at the right time and some bigger fool is willing to overpay. After all people made profit trading Pirate bonds too. Heck you could might even be able to spend 10 BTC to make it look like that happened.

Also, if cryptx gets delisted and goes private GigaVPS style, it will be impossible to objectively state if it will still be "possible" to ROI since you wouldnt be able to sell and thus have no market price. Unless you accept that under those circumstances, the value of the bond itself is considered zero and only dividend payments up to that date are considered.