Diavel is 100kg less weight than RIII. If Triumph engineers are serious about competing here, they must manage to come ballpark close to 300kg wet (now 330+kg dry), at least. Or better below 300kg. Than yes, it does make sense to do it with all the limitations of Euro regulation in such case. And it does make sense to place deposit
In my opinion, the new bike will have to look very different due to weight loss - much less steel parts, consider aluminium frame, more magnesium, titanium parts, maybe even fake tank, less fuel capacity etc. Just my 0.02