I'm sure there are people in Juventus who'll be able to do all the calculations and decide if it's an offer worth taking, but this amount isn't, or won't be as great as it sounds right now.
I'm sure you noticed that small English teams are assumed to have made the offer and I believe you know how come they're able to do this. It's the EPL TV rights starting in 2016-2017. The last placed EPL team will be getting ~140 million euro annually from TV rights. And there are 20 EPL teams. Those 7th or 8th placed teams (lets say some random team like Crystal Palace or Southampton) will be getting ~200m euro a year from TV rights. Twenty EPL teams will have no problem offering 20, 30 or 40 million euro for random players and pay them top wages. Now it's a fight for higher positions in the EPL, which will get the teams more money.
In short, 27m euro won't be the 27m eur we know right now. Every single football player will become much more expensive in the summer. So, if we sell Zaza for 27m euro, these money will be enough to buy us a Zaza. More or less, these 27m eur will be an equivalent to some 10-15m euro of yesterday, perhaps even less.
We seriously must do some buying job this winter, because it might be the last chance to get what we want, before we're left with what Barca, Real, PSG, Bayern and entire England (including some punks like Bournemouth) don't want.