Tadic hasn't signed for Everton, even if he did why does that mean Saints will be relegated? Even without Shaw, Lallana, Lambert and potentially Lovren & Schneiderlin there is a lot of quality still at the club for Ronald Koeman to build on.
Have you seen the squads of the sides below us last season and the newly promoted sides? They really are nothing special. It'll take a disastrous summer of recruitment for Saints to be in the relegation zone next May. Ronald Koeman hasn't left a Champions League club for a laugh, his appointment is a show of ambition in itself. More so than for example West Brom appointing Alan Irvine don't you think?