The thing about Suarez being the difference between top 4 or not is a bit irrelevant considering Liverpool will win the champions league anyway.
The defence is going to be an even bigger issue this season, because without Suarez, the team will not be as efficient in front of goal, so will have to bee much more effective at the back. You can't get rid of Johnson though, no one will take him on those wages, which in turn, makes it difficult to justify buying another right back who would probably command fairly high wages given the quality you would be expecting. I think this could be where Wisdom can come in and stake his claim for a start, he's much more solid in defence an reliable in possession than Johnson and Flanagan, but doesn't have the dynamism to get toward the byline. Hopefully he is ready and good enough.