Kevin has told me that Archie will be proposing to Veronica in issue #600.
Thankfully, looking this up it appears it is a 6 part series, so it's likely he won't marry her.
Which is good. Veronica treated Archie so badly. Bettie, although a bit of a pushover- really loved him and treated him well. I wouldn't want to see Archie with Veronica. Besides which, what would the storylines be like after that?
At least he isn't marrying Cheryl Blossom.