Spurs sold Modric and are now being pressured in to selling Bale, Arsenal sold Fabregas and Van Persie, Porto sold Falcao, James Rodriguez and Moutinho.
Spurs sold Modric and I would argue that they are still missing what he brought to the table; baring the miracle year from Bale I believe Spurs looks worse off without Modric.
Arsenal have a certain fight and balance which means they can do this sort of thing; lose top players and still have the drive to keep 4th place; we do not really have this drive, or we would have done better than we have done the last few years, and we certainly don't have the same consistency as them.
Porto live off selling their best players: with easy access to South Americas best at cheap prices, and league that is easy enough to win with a weakened side but hard enough to develop prospects into top class players, and a relatively minimal expectation in the Champions League all add up to selling their best players for loads is a very viable option for them.
Truth is we COULD come out of this with a better team than before, but it's hardly a given and will be extremely hard to pull off; we either get potential who won't be as good as Suarez but may be in the future (at which point we have the risk of these players wanting out because they believe they have developed beyond our ambitions) we try and by a couple of players which replace Suarez as a whole which again is very hard because we have to identify the limited number of players who will do this, and then we have to hope they come here, or finally we could spend the money on many positions to strengthen the entire team, which again may not work out, since we may not get the right players, and even if we do, we may become a well functioning team which misses that little spark that can win games from nothing.
I'm not saying these scenarios will happen, just saying they are fesably possible, and also saying that we shouldn't kid ourselves that replacing Suarez is going to be an easy task, or that it is the best possible situation the team could have had.