In today's gaming market, a franchise that's 15 years old would typically have around 18 entries (looking at you, Assassin's Creed), but for the Super Smash Bros. games, the number of titles in the series can still be counted on one hand. Franchise entries have never been rushed to market, and while one might think Nintendo would benefit from releasing the games a bit more frequently, it's a testament to the developer's determination to make the best game possible every single time.
One benefit of the long wait between games is that players can watch the evolution of the series over time. Super Smash Bros. has remained true to its core - that is, beating up on classic Nintendo characters - but over the years, the game has changed and evolved so much that the newest entry in the series is nothing like the classic that preceded it.
It's hard to really speak on the future of Super Smash Bros. 3DS quite yet: we thought the game was a blast, but whether or not the community embraces the title has yet to be seen. The game is easily the largest in franchise history: 48 playable characters, all with customizable options, 29 stages, new modes and better online play are all part of Super Smash Bros. 3DS.
Nintendo has also made it clear that complaints about Brawl's gameplay have been addressed, with random tripping being removed entirely and characters feel more diverse across the board. If anything Super Smash Bros. 3DS feels like Nintendo's way of thanking fans of the series for their dedication over the years.
As one of Nintendo's flagship franchises, every new Super Smash Bros. is an event on its own. There's no other game quite like it, and while others have tried to capitalize on Nintendo's success, Super Smash Bros. manages to stand head and shoulders above its competition.
As for the future, the Wii U version of the game is still set for release this holiday season, and anything after that is anyone's guess.