Yea!
Lois tells him her deep dark secret. I love how calmly Clark accepts Lois's admission that she's from the future. If only it was easy to prove one's otherwise crazy assertions are true by use of a simple iPhone app.
I think you've created the perfect iPhone commercial. Following Lois into the future to see more of such technology must also interest Clark.
LOIS:
I'm actually from the future. See, here is my iPhone.
CLARK: Very interesting. /checks out iPhone/ I believe you. Now, I can tell you my secret. I'm actually from a shooting star.
LOIS:
You're nuts!
CLARK:
No, I'm from outer space. /hovers off the ground/ What do nuts have to do with it?
Since Lois is part of the Baby Boomer group, that group existed mostly due to their dads going off to WWII, coming home, getting married, and wanting to make up for some of the time they lost during that conflict. Clark stops WWI, then the setup for WWII does not exist (Germany in ruins leaving the opening for Hitler), her world is radically changed, Sam and Ellen probably don't meet, and she does not exist. Then we get into the time loop thing because if she does not exist, she does not jump back in time, she does not warn Clark, Clark goes into the Hotel fire and loops back and is not there to stop WWI. Well you get the picture. I suspect one Mr Wells makes an appearance shortly...
Sorry, Mike, while all your other conclusions about the repercussions of Clark changing the future may be true, I must dispute your reasoning that Lois is a "baby boomer". Her parents are baby boomers, children born during or shortly after WWII. Lois comes from the next generation (unless Shayne had her born even later than 1966). Her father is more likely a Korean or Vietnam War vet, unless he was in his 40s when she was born.
You do make a good point though, would Clark chance losing Lois completely and creating a time paradox just to try to stop WW-I? I'm sure this possibility will occur to him while he spends all night debating this.
Either he will see Lois safely into the time portal and be left behind and wait the 100 years (or 80 years to 1993) until he can meet up with her again (while keeping tabs on her and making sure she'll survive). *Or* he'll also end up in a time portal, but somehow learn to manipulate it's use or predict its occurence so he can travel through time, visiting the different eras and learning about its history and technology before leaping forward with the next portal.