There's still a lot of games left so it's true what you say anything is possible including Newcastle not being in the top four, but the advantage that Newcastle has is that they have no other competition besides the Premier League so they can really focus on one goal which is to get spot in the UCL next season, different from other competitors who still have to compete in other tournaments
Moreover, this advantage of concentrating on one tournament this season is much stronger than in any other. Due to the World Cup, the calendar of games is very compacted and teams that play in several tournaments will suffer greatly compared to those who play in one. I think that the difference will be felt by the end of the season more and more, and even some top clubs will fall into failures.