I think it will be very difficult for Arsenal to repeat those results this season and that the top European clubs, such as PSG, Bayern and Real, are still a level above them, financially and organizationally.
No doubt about what you have said, but if only Arsenal can still maintain same energy and confident as of last season, anything is possible. I know those teams you just mentioned are great team and they own the champions league but football present is actually not based on names this days because even smaller teams are now pulling storm you can never imagine.
A smaller team cannot pull storm in the Champions League because it's for the big clubs. Most times, it's big clubs in their various leagues that do win the title and not small teams. If you have observed this competition for long, you will see it that it's only the big names that do win it because they have the quality and pace till the end
Unfortunately, this has been the case for the last 25-30 years since the 3-foreign player limit in football clubs was lifted.
After that, this competition became a bit boring because only the financially strongest clubs won the Champions League, and in the last 15-20 years, the Champions League winners have always been the same 6-7 clubs, Manchester City, Liverpool, Chelsea, Barcelona, Real, Bayern and PSG.
Money really makes a big difference in football today and financially weaker teams are simply not competitive in the Champions League.
I remember some long ago times, which will obviously never happen again, when clubs like Crvena Zvezda and Steaua won the Champions League.