Can't wait for this movie ...
I am sure it cannot be as good as the first movie. I think TMFE was so good because it was so mundane and the characters all seemed to believable. I figure they will try to upgrade the plot, bring in scientists, the government, or a big chase scene, like all of the movies and TV that have had a similar theme. Car crashes, explosions, gun shots, etc. I hope not, I hope they realized what they had with the little gem and try to stick with that simple plot.
But, one thing I did realize about the caveman, John Oldman, is that if you wanted to see if he was real or not ask him about language. He should be able to speak quite a few languages or offer some enlightenment about how they developed. If there was a weak spot I think it would have to be that any "cave man" would be reasonably expected to know a lot about language.