I think that Phil and Claire will be carrying out their "five-more-years" plan and vacationing somewhere. Luke turns out to be a computer genius who has a bright future in coding and is heading off to college. Alex has a successful career, and has married a jock, male version of Haley(dumb/lovable). Haley has her own fashion label, and her business partner just happens to be her husband and baby daddy, Andy. Jay has retired and the business is now Claire's. He is very serious about learning Spanish and he and Gloria now vacation in Colombia. Mitchell becomes one of the most influential environmental lawyers in the country while Cam is coaching a university football team. Lily is sassy as always and continues to be the person who grounds her parents.

I imagine that the final episode will very subtly hint at Jay's death, but not in a way you can catch if you're not looking out for clues(think The Time Travelers episode of HIMYM). The episode's theme for the confessionals as well as the plots will be what family means.

One of the final scenes will be a throwback to the very first scene(Claire/Phil yelling at the kids to eat breakfast)except this time, the kids are grown up. Haley comes downstairs, baby in her arms, Alex's fingers are intertwined with her husband's and her hand is on her stomach.

The final scene, I think, will be the whole family sitting around Jay's dining table, having their Sunday pasta dinner. Jay's eyes are--just barely visibly--glassy. The last confessional will be Jay talking about how much his family means to him. He almost gets emotional, but his last line is some sort of joke. He smiles, and you hear that music that comes on whenever there are very sweet moments in the show(throwing mud at each other/dancing around in the street/having dinner). And the show ends like that.

I hope, anyway.