I don't think that means that it is the end of TLK as we know it. Keep in mind that TLK2SP came out before TLK 1 1/2 and so they weren't exactly planning on having this being a Trilogy at that point. The DVD only says that because the TLK2SP DVD came out after 1 1/2 did, or at least the 2 Disc Special Edition one did, and it's hardly befitting to consider TLK 1 1/2 as being part of a "Trilogy" since it wasn't really a sequel or even prequel, but I don't know if inbetweenquels count towards Trilogies but whatever. lol. I still have hopes for a new TLK movie in the future though and even if the original storyline for TLK has come to an end with Simba's Pride, that doesn't mean that a new and totally original storyline couldn't be used with the TLk name.
Would be quite a departure from what we know and love but like some people say, it might be better if what's already been made isn't tampered with anymore.