I don't think you will ever see a full set cart because that means no more sales. They had the capabilities or doing a full set cart from the start (minus a title or two with odd protection), but they didn't because it is more profitable to sell a series of ever escalating carts to the same people.
I have two different Neo Geo multicarts, both are missing multiple titles from the Neo Geo launch, while they both have 4 times as many versions of King of Fighters than ever even existed. The same Chinese bootleg crap as always, they don't respect their customers anymore than the people whose games they are pirating. Why make a good product when you can just inflate a number with a crappy clone.
I would think a new one is coming out soon because sites like jammaboards.com are dumping the 161 carts for >$100. Here's hoping for a full set cart! 