It's interesting to me how Casino Royale
spent most of its time showing us how Bond became "James Bond, 007", including his adversarial relationship with M as the closest thing he had to a mother figure... and here we are in Skyfall, seeing an end to that specific element of the story - he's absolutely fully formed as "James Bond, 007" - complete with a Q, Moneypenny, and new M - and Judi Dench's M exits quite fittingly I think in the childhood home (which was also summarily destroyed) of James Bond himself.
Too - you have to wonder about Daniel Craig's Bond - all the women he's loved (or at least had dalliances with) have died or been killed. Vesper, Solange, Strawberry, Severine, and now M. Might be a good idea for him to lock it up, if only for the female population!
In a lot of ways, Skyfall
is the denouement of the (thus far) Craig "trilogy", all at once ending beautifully but also rebooting nicely as well. Bond's last words in the film, I think, are a signal to us (the audience) that though its still going to be Daniel Craig's version of Bond, we are now really back to the basics of what the character has been in cinema - "With pleasure, M. With pleasure." I don't think the next film will be about revenge (as Quantum of Solace
was) or about protecting someone close to him (as Skyfall
is) - but rather a return to form.