Nobody has ever been all that excited over the Divergent movies. They never measured up to The Hunger Games and couldn't measure up to The Maze Runner, either. There was even less enthusiasm over Lionsgate's plan to make the fourth movie, Ascendant, a TV film because Allegiant tanked so hard. Shailene Woodley certainly never sounded interested in it, but she didn't officially slam the door on it until now.
Speaking with Vanity Fair at the premiere of HBO's Big Little Lies, Woodley kept it short and sweet that she was done with Divergent, saying "No. I’m not going to be on the television show."
Obviously since she was there to promote her HBO series we know this isn't Woodley having an aversion to working in TV. But she's right that she signed a contract to star in a big screen franchise and TV is a totally different world in more ways than one. Different money, different expectations, different scheduling, different everything. Doubtful they find any of the original cast willing to return, and I'm not sure the series will work without them. Then again that City of Bones series Shadowhunters just began its second season on Freeform and seems to be doing well.