It seems that in this context "by-and-by" doesn't mean "before long" or something of the kind. It's an extract from Meredith's Diana of the Crossways. I'd be grateful if you could explain what it means; my only guess is that it is something like "your health" because the characters are about to drink champagne. Thanks in advance!
'I'll never live to hear a lady insulted.'
'You don't mean to say you're the donkey to provoke a duel!' Mr. Redworth burst out gruffly, through turkey and stuffing.
'And an Irish lady, the young Beauty of Erin!' Mr. Sullivan Smith was flowing on. He became frigid, he politely bowed: 'Two, sir, if you haven't the grace to withdraw the offensive term before it cools and can't be obliterated.'
'Fiddle! and go to the deuce!' Mr. Redworth cried.
'Would a soft slap o' the cheek persuade you, sir?'
'Try it outside, and don't bother me with nonsense of that sort at my supper. If I'm struck, I strike back. I keep my pistols for bandits and law-breakers. Here,' said Mr. Redworth, better inspired as to the way of treating an ultra of the isle; 'touch glasses: you're a gentleman, and won't disturb good company. By-and-by.'
The pleasing prospect of by-and-by renewed in Mr. Sullivan Smith his composure. They touched the foaming glasses: upon which, in a friendly manner, Mr. Sullivan Smith proposed that they should go outside as soon as Mr. Redworth had finished supper-quite finished supper: for the reason that the term 'donkey' affixed to him was like a minster cap of schooldays, ringing bells on his topknot, and also that it stuck in his gizzard.