Imo, not signing Gotze was a blessing in disguise. Mane would probably improve the side more in terms of having pace out wide. You airway l already have enough attacking midfielders. The main obstacle is finding players willing to go without European football for maybe a season. Will Karius be good enough to win the league? Will Liverpool sign a credible Moreno replacement? Will you sign a top centre back? A few other weaknesses need rectifying and I can't see how you'll get the required players. Anything can happen in football though.
With Matip, who by all accounts had another excellent season in Germany, and Lovren, who was playing as good as any centre back in the EPL the second half of last season; I don't think the need for that 'top one' is there so much s it was the first half the year. We'll need another centre half for depth purposes mind. Skrtel's mercifully gone. Illori more than likely too, He's nowhere near top flight standard. So that leaves the very inexperienced young Gomez coming off a season long injury, Lucas who may or may not be pushed in there but hes not really ideal with his lack of pace, and Kolo who hopefully will be retained another year as the 5th CB. (NO idea why that's still not been attended to. Seems an absolute no-brainer to me both for reliable, veteran depth and a fantastic dressing room presence for everyone. Young and old. So another reliable one along the lines of a Subtoic and what he did for him at Mainz and Dortmund for many years would be perfect. Plus if Karius is just a solid 'keeper, something Mingolet will never be on a consistent basis, that automatically makes everything solid.
I can see Moreno being gone and two LB's coming in. The Leicester lad who you've been chasing apparently favours a move here. So he'd be sound as good young depth in now without having to pay a heck of a lot more a year or two down the line. And then an experienced one, be it Cologne's Hector or whomever that's a solid defender with Moreno completely binned. (Thought Smith might be the young back-up but the longer the year went on he looked as braindead as Moreno. He's just not got enough for the very top level.). RB we're solid with the uber consistent Clyne and Flanagan backing up.
To your other point on Gotze (still don't think that's anywhere near dead as regards ourselves but we'll see), I'd beg to differ on two counts in having enough attacking mids. Firstly Coutinho. World class on his day. Average frustration on others. And the later outweighs the former when it comes to his consistency. The UEFA Cup Final is a glaring recent example of him completely disappearing when he should, at this point, be taking hold of games like that if he's ever gonna' live unto his ability. Right here, right now, if Gotze came in, Phil would be my odd man out to start with Lallana and Firmino, who hopefully can only get better his second season, the two to start alongside Gotze. And then you've also the added bonus of Firmino and Gotze being able to play up front as perfect forwards for the way Klopp plays. Considering Benteke's more than likely gone, that lesson's the need for a striker with Sturridge, Origi and Ings along with those two.
A top notch, mobile DM is far more a priority than a centre back to allow Can, Henderson and Grujic to get up and down.