What you said certainly makes a little sense because in every season all teams that have money will continue to spend the best players to improve their team's strength so they can compete with all rivals in the Premier League. I also agree with what you said that teams like Manchester City and Arsenal will still be quite difficult opponents for all other teams next season, not to mention if there are surprises from teams other than them such as Newcastle and Nottingham Forest. So clearly there is no certainty that Liverpool will be much better than this season in the Premier League next season.
Nottingham made a big mess yesterday, in a match where they only needed a win, they couldn't score a single goal and even managed to lose a home match. Well, the best man wins and it seems Nottingham are not ready to play in the Champions League next season. Today City will host Wolves, and now that City's game has started to improve they must bring things to a logical conclusion, they will strengthen their position to stay in the top 4, they most likely will not get to Arsenal, but they can compete with Newcastle.
Nottingham Forest could not maintain their dominance, but they failed against Brentford, losing their important points. Yes, their current performance seems that they may not be ready to qualify for the Champions League for the next season. Their game has been much worse than before and their performance is not at all logical at the moment but they seem inattentive. However, Manchester City is trying to maintain their position and maintain the top position in order to play the Champions League next season. If the City team can stay in fourth position, then they will definitely have a chance next season, but their performance has been much better now. If the City team can maintain their performance properly then they will definitely be able to compete with Newcastle, but they must be focused.