Shadow is still about channeling so beside both using shadow magics and dots i dont see similarities on both identities, in fact it looks more of a TBC/vanilla-esque flavour than anything else
Destro has never been as rng as fire, even with OMGRNGMASTERY, if you dont recognize that you never played fire (you could argue that BRF double IB was easier but still much more rng than destro)
About demo, well i honestly cant think of any more iconic dot than Doom for the warlock class, and since demo is the only spec having it i really cant see your point, considering they didnt really prune any iconic ability beside Meta and its spells