Um, since 2011-2012, Mitchell scores at a .098 goal per game pace, which averages out to about 8.09 goals a year (less than his career average of 8.23). Last year, at 31 years of age, was only the second time in his career he's eclipsed double digit goal totals. So, not I don't think we can expect 10 goals a year from Mitchell.
By contrast, Eller since 2011-2012 is averaging .178 goals per game, which averages to 14.65 per season.
The difference between Mitchell and Eller over the last few seasons is 6-7 goals. That's pretty huge.
As for Danault making up the difference, he hasn't even scored 7 nhl goals so far. Not only that, it's not a matter of making up the difference. Danault would have to score roughly 14 goals a year from the 3rd line to match Eller's output from the same position (. Not an easy feat, especially since he just barely eclipsed that goal total in the ahl) while Mitchell would have to continue to get career highs just for the Habs to break even on the combined output of Lars and Mitchell last season (which clearly wasn't good enough because they finished terribly).
I get it, you don't like Eller because there was a fan following and you like to go against the grain, but please assess the situation a little better.
Essentially, you're hoping that Mitchell continues to have career highs in his mid-30s while Danault will suddenly triple his career output. Color me skeptical.