According to a report by PTI, If Shreyas Iyer is not fit for the Sri Lanka tour, the captain will be either Shikhar Dhawan or Hardik Pandya for the Indian team. A report by Sportstar also suggests that Shreyas Iyer unlikely to be fit on time so he won’t be available for selection in the Sri Lanka tour.
Amid all these numerous debates are going on between fans that who should captain the Indian squad if Iyer is not available. Some have views that Shikhar Dhawan is the best choice while others say that Hardik Pandya can prove to be a better option.

Captain Virat Kohli and his Vice-Captain Rohit Sharma will be taking on England in the five-match Test series, At the same time in July Dhawan and Pandya are set to feature in the second-string Indian side for the Sri Lanka tour.
It is to be noted that Shreyas Iyer is currently recovering from the injury and is unlikely to be available for the tour otherwise he would also have been a priority for captaining the squad. Now either of Hardik Pandya and Shikhar Dhawan is likely to be leading the side.
Although there are no official statements on this aspect from BCCI. All these dilemmas will be clear only once the team is officially announced.