Of course! Okay, this is going to be a bit subjective but, I'm a big fan of that egocentric guy, I love to see him being a badass.
And so, my first reason is from the question mark he put on the novel that Watson was finishing. Should Sherlock Holmes just end there, the ending is just too plain. I'd love to see Gladstone too.
Second is, the Master of Disguise seen on facebook, come on. Where in the world will Downey disguise himself with that nose on that kind of setting?