First, ML3 is an Oscar worthy movie and Scott Bakula is a natural treasure.
Now that being said... I can see a 4th season. The overall focus on Rebecca overcoming the lost of her husband. (Who died in a plane crash) and Ted returning to coach the U21 w/ his son moving forward in life.
Concept:
The season fast forward four years, in that time. Ted son is older and looking to continue playing at the 16 and 18 yr old level. Ted has to see him off. He never remarried his ex-wife but he has not moved on with his life. Higgins asks Ted to return to help train the U21 group.
Rebecca husband died in a plane crash. She is crush and trying to raise her stepdaughter. She is a wreck and having a hard time dealing w/ the lost so Higgins, Beard and Kelley realize that they need help from Ted. They bring him over to help w/ the U21 but in reality they are hoping that Ted spirit will rub off on Rebecca.
Roy is now the head coach w/ Nate and Beard assisting him. Roy should be happy but he is not because .. he is Roy. Roy is also worried that Ted is coming to replace him. Since Ted left, they have been stuck in the middle. They lost Jaimie due to money and a few of the players and the team is no longer the team that Roy played with.. they are strangers to him. The team over time has moved on.
Keeley company has excelled but she never settled down. She is worried about Rebecca and works w/ Higgin to get Ted back. She is also avoiding Roy as she has a relationship that he would not approve.
Higgins - well he is Higgins.
Yes I still think Ted and Rebecca is the end game.. with both finding happiness and her enjoying his biscuits.