WWE will be doing fewer pay-per-views in 2018, according to Dave Meltzer on Wrestling Observer Radio. Meltzer stated that there will be no months with two pay-per-views until April or May. The next RAW pay-per-view will not be until February in Las Vegas, NV. Meltzer said there "probably" will be a pay-per-view in March before WrestleMania in April.
It should be noted that this year featured no months with two pay-per-views until April as well, which had WrestleMania 33 and the RAW branded Payback show. The first month to feature separate RAW and SmackDown branded pay-per-views was June. In addition to June, the other months that featured two separate RAW and SmackDown pay-per-views were July (Great Balls of Fire, Battleground) and October (Hell In A Cell, TLC).
Following The Survivor Series on November 19th, there will be only one more WWE pay-per-view this year, the SmackDown branded Clash of Champions show on December 17th from the TD Garden in Boston. That leaves 2017 with 16 pay-per-views, 6 for RAW, 6 for SmackDown and 4 dual-branded. 2016 had 15 pay-per-views, however the brand extension happened mid-year.
As noted, on last week's episode of WWE SmackDown Live, WWE announced that AJ Styles would face Rusev on this week's show, with the winner joining Team SmackDown at The Survivor Series. Plans were changed the following day to Styles facing WWE Champion Jinder Mahal on this week's show for the title. Meltzer noted that the scheduled main event for next month's Clash of The Champions pay-per-view was Styles vs. Mahal for the title, however it's not known if that was changed following the match now happening on this week's SmackDown Live.