I'm a long time player of animal crossing that just got New Leaf this past Christmas.I know in previous games that depending on were you live in the real world, you get different events and festival items in the Animal Crossing game.
However in New Leaf it seems that many regions have the same holidays and they just celebrate them on different days. I also have heard that you can buy any non local items from the shops at some point. (Such as buying the Ogre Mask at the Able Sisters)

So my question is, does New Leaf still have holidays, events, and items you can only get regionally? Or will I be able to buy all items in the shop or receive them via different events?

There are quite a few regional items that you can't get in other versions. The thing about the items being sold at the Able sisters is not true. Sometimes Nintendo will make a regional item national DLC, but not always. However, ACC is great for getting the items you can't get otherwise! There are plenty of people willing to give or sell you the items I wanted throwing beans, which you can get during a holiday in the Japanese version, and I was able to get them through this site for pretty cheap. I've gotten many items this way. Just be aware, sometimes regional items can be expensive due to demand. Just look around on different threads for the right price

Watch the trading board for cataloging parties for orderable Japan items.
I was able to get most of the hats, wigs, campus series and some cooking items.
If you get a Showcase house they might items inside.  I found the rice cooker when I looked thru someone house.