The problem isn't how much the game would sell, as every DMC game has sold over 1million, hell the last one sold the most out of all the games.
The problem with video games these days is developers/publishers having absolutely no idea how to keep a budget for their games. Your game should NOT have to sell over 2million copies to make money. That is absolutely ridiculous. The last I heard of Catherine it did about 700k and was considered a huge success
At any rate I hope they never make DMC5 or DmC2. They'll just ruin it in an attempt to grab the casual audience.
Yet 3M sold for Kingdoms of Amalur was deemed a failure.
Also what is wrong with trying to grab the casual market and making money. I mean usually I am on your side of the argument, I don't want my game to be casualized to the extreme, but they can still make a difficulty for them if they still give you the challenge you crave to try to keep the series you love afloat.
You see Dark Souls 2 devs are talking about tutorials and explaining the game mechanics in the game and that to me defy the purpose of the game which is to go on an adventure and discover thing and mechanic as you go, but if they were to make the tutorial optional to appeal to the Skyrim crowd and leave the game as it is for those of us who like it the way it is I wouldn't mind it.
if my idea about FROM is right, they will keep the whole tutorial very2, player base discovery
maybe stuffs like "approach enemy from behind silently to deal great damage", "push analog slowly to walk"<- casuals can't tell the difference about walking or running "attack while falling to deal great damage" "R1 : right hand attack L1 : left hand attack, R2 : strong right hand attack L2 : strong left hand attack"
pretty much VERY basics to survive, it helps, but is up to player to try
as for DMC5 bring back old dante & original mundus, continue from DMC4 & mundus keikaku to invade human world once again, and trish clones (several & drops weapon/sacrificial relics for you)