I certainly hope that the series will not be flooded with the elements that don't fit into LBT in my opinion, but are included by many fanfiction writers.
Like aliens, duels with stalagtites, time travelers, and crossovers with other franchises? That might happen occasionally, but I cannot see the people brainstorming ideas for episodes going, "Oh yeah, let's have a horde of ninjas flipping out in the Great Valley, along with a cameo featuring Capt. Jack Sparrow!"
BTW, I've always felt confused about what you mean by "non-LBT elements". Do you mean things that haven't appeared in the series before? That would mean an opposition to the introduction new species of animals, new environmental hazards, or new morals. Or do you mean things that don't make sense in a prehistoric setting? Of course, the "prehistory" of LBT involves an amalgration of flora and fauna separated by time (often millions of years) and space (often thousands of miles) coexisting in the same ecosystem, so the series doesn't seem to care about what would happen in a real Mesozoic setting when it comes to developing story ideas.
Personally, I have no problem with stuff like aliens, time travelers, sorcerers, lizardfolk, or other unusual things appearing in the series. For me, LBT is a fantasy world, so I don't have strict rules on what can and what cannot appear.
