They are still there. When I went in April 2015 there were a lot of babies. So maybe the ones you saw were some offspring from a year or more ago.
Yes, according to the Cincinnati zoo, 5 of the 6 were born in 2014, in two separate litters. The 6th was the father of the ones at the Cincinnati zoo, according to the keeper there. By coincidence, I was at Animal Kingdom park in mid-June, and there were lots of meerkats. I would just really miss them if they weren't still there when we return.
I've often wondered why they don't display the lions up close as they do the tigers. Lions are my favorite animal and it's really hit or miss (mostly miss in my experience) that you'll see them (awake at least) on the safari. I thought maybe it was the difference between lions and tigers in captivity, but according to the OP, it seems the folks in Cincinnati don't have a problem with people observing them more closely.
We go to the Cincinnati zoo often, at least 2-3 times a year. The new lion enclosure was built about 2-3 years ago. For the first two years or so, the male lion would hide in the back. Occasionally, you could catch a glimpse of him. This was so much the case that there were times we debated whether it was worth our effort to go over to that part of the zoo. This is the first time that he, the female lion, and the cubs were all up by the window. I think I took about 20 pictures of them.
The Cincinnati zoo has all the cats in enclosures with the glass to get them close for people to see them. Up until 2010 or so, the tigers were in a deep ravine, but, when they remodeled the cat house area, they made the glass windows to better see the animals. Cincinnati zoo has always been very active in cat research. Personally, I wish zoos could be more open about where animals go in breeding programs. In 2008, the Malaysian tiger had 4 cubs. Then, they remodeled the area, and she and the cubs were gone. But, we were quite attached to the cubs, and would like to know how they are doing.