Not being familiar with first-century linguistic usage, it's not entirely clear what is meant.
Certainly, one main message of the Gospels is that repentant sinners who seek Christ can receive salvation. Indeed, since all are sinners, the only way to salvation is through Christ.
I therefore do not take Paul's words in Corinthians to mean that nobody who has ever fornicated can enter the Kingdom of God, nor anybody who has ever gotten drunk, etc.
One difficulty with terms like "drunkard" or "fornicator" is that they refer to quantitative concepts qualitatively, without clarification. As such, it can be unclear whether the terms are meant narrowly or widely.
To understand what I mean, consider other verb-derived nouns like "writer". Would you call anyone who has ever written anything, anywhere, a writer? Or would you only use the term to refer to a small subset of such people?
Without being familiar with first-century linguistic usage, I can't really say with certainty what Paul meant. Certainly the term would probably include people who engage in wild orgies nightly with half a dozen partners. But would it include someone who had sexual relations with a woman he ended up marrying?
For my own actions, I try to stay within the straight and narrow (adopting fairly broad definitions of those terms). On the other hand, I cannot say with certitude that broad definitions are correct.
Well, there are many people familiar with biblical Greek who have written commentaries.
In fact, some of them even knew St. Paul or St. Paul's close friends. There are called the Church Fathers, and you can find very easily what Church Fathers thought about fornicators who refuse to admit that fornication is both immoral and sinful.