I think the times has blown this a wee bit out of proportion...
Disney didn't say Tangled was the last one ever.  It could just be the last one we see for a long time.  
This is nothing new.  Between "Atlantis" and "The Princess and the Frog" there was an 8 year gap of no movies with any kind of princess.  The "Disney Princess" movie is a more modern notion (thanks to Disney making a whole franchise out of the idea) than in the company's early filmography.  Most of the princess movies were created after "The Little Mermaid" than before it.  
Princess Eilonwy was 4 years before Ariel
Maid Marian was 12 years before Princess Eilonwy
Aurora was 14 years before Maid Marian
Cinderella was 9 years before Aurora
and Snow White was 13 years before Cinderella
Personally I think they're running out of fairy tales to adapt.   But again...not a huge deal.  The majority of Disney films don't have a princess in them anyway.  *needs moar Fantasia*
No fear.  Pixar is working on their first "fairy tale" movie, "Brave".   
