2017 wasn't a very good year for traditional retailers, and next year is unlikely to be any better, former department store executive Jan Kniffen told CNBC on Wednesday.

"This year we'll see more stores closure announcements than ever in history, and it's the best year I can ever remember in retail [overall]," said Kniffen, CEO of consulting firm J. Rogers Kniffen Worldwide Enterprises.

During 2018, "we're going to see more bankruptcies, more store closures. That's not changing," Kniffen added in an interview with "Squawk Box."

Nearly 7,000 store closure announcements were made this year, according to research and advisory firm FGRT, up more than 200 percent from a year ago. The closures came as consumer preferences changed and sales continued to migrant to online platforms such as Amazon.

Kniffen, who was a senior executive for May Department Stores for 20 years, said most retailers had a decent holiday season but the "winners and losers" will not change next year. He added that "bad retailers" will get hammered by the GOP's tax overhaul.

The tax bill reduces the corporate tax rate from 35 percent to 21 percent.

"The guys who are maximum taxpayers at 35 percent are going to 21 percent. They save 14 percentage points," Kniffen said. "People who don't have the advantage, because they are bad retailers and don't make money, are going to get pounded."

"The lesson is the world is still going online, that hasn't changed," he said. "And the lesson is we're still going to see lots of stores close."