The best way to complete the smallville series arc would be to:
1. show Clark learning how to fly (as in finally perfecting it) like in the 2nd episode of the animated series (by curiousity and accident)
2. show the transition of Clark to Superman from the time he decides to leave smallville to learn more about his powers and gain degrees (each episode in the final season carefully plotted to lead to the next but where it's a "X no of days/months/years later" kind of progression, while being logical) so we actually see clark's transformation in attitude and his decision to be a hero, and even an episode on the decision of choosing his disguises & personality.
3. Show his entry into the superman scene as :
a) clark kent reporter -- recognising but not being recognised by lois who by then has lost major aspects of her time in smallville with him, to clearly recognise the two identities... although she merely remembers clark as a helpful, concerned teen friend, but can hardly recognise him or relate him to the Superhero he is. He passes off as clark with specs...tellling them his hard studies got him severely short-sighted. And with Clark taking all the spotlight close up, Superman can maintain his secret as a soaring public figure.
b) as Superman in rescuing the space shuttle etc...as per the traditional superman Mythos and similar to the animated Series, where he'll encounter the 'new & badass' Lex Luthor (whom clark remembers, but who lex doesn't recognise). moreover while Lex's obsession is Superman, he'll be more personal with clark as a healthy rivalry whose reporting challenges lex's exploits.
For Lex, Krypton and Superman are related, but Clark was affected by the meteor in a similar way that he was [coz he has seen clark shed blood many times in smallville, and clark's bumbling persona could be attributed, by lex, to 'seeing the real world']. His whole attitude will prevent him from seeing the 2 of them as one and the same...not to mention the public opinion and awe...that's just as misleading and distracting.
4. In the Meantime, as Superman, He will meet Cyborg, The Flash, Aquaman all in their superhero persona.
5. The Final episodes of the Final season will show Clark/Superman falling in love with lois, and after settling down in Metropolis, the last episode would literally play on when of the great superman mission in the Comics/Animated Series (such as meeting Darkseid). The last 2 episodes will be similar to Father's Day episode in the STAS.
The Final Episode will see Superman flying off to meet Darkseid in Apokolips in the end with the final words in the credits:
"Superman flies off to face his destiny, to protect Earth, his home...
In the Near Future:
- He will found and lead the Vigilante Corp Justice League
- Face the Greatest Villians and Crisis ever taken on by him
- Repeatedly test his sworn duty, his morals, values, motivations to protect and show Earth the light to live a great life"
- While he protects his identity and the people he loves and has loved
- Becoming the Greatest and most loved legend the world has ever seen.
The Legend Lives on...."
and then ends with the ending music of the First Season of Smallville.