Arsenal is the only team that can compete with Manchester city as it stand, they have got the right player to give Manchester city a tough competition next season. last season they bottled the league because they got no good squad to rotate, every weekend it was just set of first eleven and they got some injuries issues too. But now they have a good bench to rotate and rest some players.
I don't think Arsenal is the only team that can compete with Manchester city in the premier league. They've got the right players alright, but Manchester City is far superior to Arsenal and this is just my opinion.
Admittedly, Arsenal suffered some setback due to injuries and lack of available players that could properly handle those roles. I still think Arsenal is a strong contender for the league cup along with Manchester United and perhaps Newcastle like you noted.
I would also like to see how Brighton would have prepared for the upcoming season. They had a somewhat good run last season and had given some big clubs hell on the pitch. I would like to see what preparations they've made for the next season.
Last season will not be the same for next season because after all, teams like Chelsea and Liverpool last season experienced chaos, especially about Chelsea. So yes, because Liverpool and Chelsea experienced a decline last season and then teams like Arsenal, Manchester United and Newcastle can fill the position under Manchester City. But, because last season is over and every team certainly makes changes in the summer transfer window, I believe teams like Liverpool and Chelsea will probably be back competing in the top zone. Therefore, Manchester City's rival team next season will not only be about Arsenal and Newcastle, because it is very likely that Liverpool will again enter the title race.