Yes, what you say might happen, that Arsenal will not be able to maintain their position for a long time, because the position they currently occupy is the result of taking advantage of the results of the match between Manchester City and Liverpool when they met. However, Arsenal also still has the opportunity to maintain their position in the current standings, although their chances are not greater because the opponent they face is Manchester City.
If Manchester City can win, then they will return to 3rd place in the standings, and that will look at the results of Liverpool's match because if Liverpool wins then Liverpool will return to the top, followed by Manchester City. However, if Liverpool lose, then Arsenal will be in 2nd place because they are still superior in terms of goal productivity. However, I don't see Liverpool losing this match, because the opponent they will face is not a strong club, so it is very likely that they will win in the coming week.
So that's why we say the match between Manchester City vs Arsenal is a decisive match because whoever wins will take over the standings if the two teams only draw then Liverpool will take over the top of the standings, what is clear is that these 3 teams still have the same chance. In the last few days I have noticed the odds for Manchester City dropping meaning more bets have been placed on the Manchester City side as the home team but there is still no guarantee that Manchester City will win.
I have seen a lot of discussion regarding this important match, as we know most people favor Manchester City but beating Arsenal is not easy moreover, currently Arsenal is the most consistent team at least in the last 7 matches. I personally hope both teams play a draw so Liverpool can take advantage like what Arsenal did 2 weeks ago when Liverpool draw against Manchester City.
It is more than taking over the standings as Arsenal is leading the table anyway. But for Manchester City a loss would be a huge setback in the fight for the Premier League title. It would distance Arsenal from Manchester City by 4 points and a far superior goal difference. It would be nine games left. I know what happened last season and Arsenal could still become nervous and miss the opportunity. Sure, they would still have to compete with Liverpool and Manchester City wouldn't be fully out of the race, but it would be a huge step for Arsenal towards the title this year, at least in regards to the competition with Manchester City.
But Liverpool could be the big winner here if they tie the game and Liverpool now has two games in a row at Anfield Road and they could create maximum pressure for both Manchester City and Arsenal. The last games are quite doable for Liverpool and I think a long winning streak could be possible. But I assume it will remain excitingly close until the very end.
They are all still involved in their UEFA tournaments, so there is no advantage for any of the teams regarding exhaustion. Injuries could always become a factor, but that can't be reasonably anticipated.