Of American-English origin, the phrase you’ll, or he’ll, etc., be smoking (cigarettes) next is used to rebuke someone—especially, jocularly, for an act far more improper or audacious than mere tobacco-smoking.

Published in the Leavenworth New Era (Leavenworth, Kansas) of Friday 28^th November 1919, the following humoristic story illustrates this jocular use of the phrase:

CONDENSED NOVELS
I—THE CURSE OF THE HOMESTEAD

Dear old Mrs. Giles was sitting by the fire, sewing shirts onto Pa Giles’ buttons. Pa Giles was reading the latest copy of the Smart Set, while puffing solemnly at his pipe, his old wire spectacles set askew on his old red nose. “I wonder where our Hiram is?” wondered Ma Giles, wistfully. Hiram was their only son, whom they were having educated for the position of village poundmaster. He was the apple of their eye—or, rather, the apples of their eyes. Suddenly, the door flew open. Hiram appeared. His flaming, auburn hair was all un-oiled, his eyes started from his head like stars from their spheres. His breath was coming in short pants. “What’s wrong, Hi?” asked old pa Giles, tenderly. “But, close the door behind you!” he added sternly. “Hi, what is the matter with you?” quavered old Ma Giles. “But, wipe your feet on the mat; how many times must I tell you?” she cried viciously.
“Father! Mother! I have killed my rival, the Postman, who tried to marry Annabella!” cried Hiram.
“Well, well,” said Pa Giles, “What are children coming to? Boys are getting wilder every day. You’ll be smoking cigarettes next. You really must learn to settle down. Now I suppose I shall have to send you to the county seat for a couple of days until it’s all blown over. Come, Ma! what do you say to a game of Patience?” And the old couple settled down to their game, while Hiram ate his supper, and made some pork sandwiches for his journey.

The earliest occurrence of the phrase that I have found is from the humoristic column Walks About Town, published in the Rocky Mountain News (Denver, Colorado) of Monday 9^th September 1889:

“John,” said a Pennsylvania avenue mother to her husband, “I am afraid our boy has been drinking beer.”
“Well, you must tell him to stop at once.”
“Why?”
“Because, he’ll be smoking cigarettes next thing we know.”

The second-earliest occurrence of the phrase that I have found is from the column A Little Nonsense, published in The Philadelphia Inquirer (Philadelphia, Pennsylvania) of Sunday 8^th December 1889:

The Road to Ruin.

He was only 8. Just one more year than 7. Yet he was a prisoner before the rigid bar of justice.
“Burglary, murder and arson,” read the judge.” “My boy, you are beginning a life of crime in earnest. If you keep on this way you will be smoking cigarettes next.”

The phrase then occurs in the column Nebraska Opinion, published in The Nebraska State Journal (Lincoln, Nebraska) of Sunday 9^th April 1893:

Congressman Kem can now ride a bicycle with neatness and dispatch. This is his latest achievement. He will be smoking cigarettes next, but the thought is painful.—Custer Leader.

Another early use of the phrase occurs in one of the unconnected paragraphs making up Mt. Tabor Items, published in The Elk City Enterprise (Elk City, Kansas) of Friday 26^th October 1894:

Orley Ruble is staying with W. W. Hall at present. He will be smoking cigarettes next.

This item about typography is from The Vermont Tribune (Ludlow, Vermont) of Friday 23^rd August 1901:

We find in the St. Albans Messenger the following:
Manchester, Aug. 18.—The first round of the professional golf match on the Ekwanok course was played this morning between George Low, the Ekwanok professional, and Brain- Manhattan . . . | 117½ | 117½ | 116¼ | 116½ ard professional who defeated Harry Warden when he was in this country last year. Low won from Nicholls by 3 up.
That linotype operator has evidently been playing the stock market. He’ll be smoking cigarettes next.

The phrase refers to something different, i.e., to pipe-smoking regarded as a typically male practice, in the following from the column The Galley, published in The Miami Herald (Miami, Florida) of Friday 22^nd October 1920:

It is easily the concensus [sic] of feminine opinion that the ideal man is one who never leaves a smelly cigar butt in unexpected places; who never calls a woman, “old top” on the street; who never says, “Now my idea of the League of Nations is—”; who never grasps a woman’s arm tightly just above the elbow, lifting up suddenly when she is stepping down or up a four inch curb stone; who never says, “well, now that you women have the vote I suppose you’ll be smoking pipes next”.