In my opinion, the people you play with and the champions you use should provide the majority of the interest.
What you're suggesting here are actually quite substantial changes that would change a large part of in game strategy, especially late into the game. LoL doesn't need changes to item amount, max level or anything of that sort. Extended masteries and rune pages would make everyone's early game more or less unique, and possibly help out somewhat.
But, in all honesty new champions, new skins and maybe the introduction of a couple of new game modes would make me more than happy
Just think, if you change the basic of how a match works now, everyone will become use to the fact and get bored of it just as they have with the current system. So that isn't a very viable option.
or it could make competitive play that much more intense