Don't really think that's a problem anymore. Can, Hendo, and Milner will hardly get knocked about.
Fine - but what will they bring to the table individually? I'd prefer to see Lucas involved ahead of Henderson.
Henderson, Can and Milner scored 12 goals between them last season. Those 3 together would be uninspiring.
Henderson was the 4th most creative player in the league last year with 9 assists, and He scored 7 goals in all comps. That's a highly respectable return. Milner had 5 goals 7 assists, which isn't bad for only 18 appearances. Can had only one goal and 2 assists, but he was a CB for most of the year, so you hardly expect him to be prolific. Plus he only had 23 appearances himself.
That's still 13 goals scored and 18 goals created from midlfield, which isn't bad, considering that Milner and Can either weren't on the pitch or were played out of position at least half the time. If Jordan continues to add goals to his game, Milner gets more time, and Can is played in his proper position and continues to develop, I don't see a problem.
Plus we have Lallana, Markovic, Coutinho, Firmino, and Ibe to come into the midfield and contribute. Danny and whichever striker we sign will also be scoring a fair few.