Salah's predicted injury is a hamstring injury. I think it won't be too serious. In the short term, the Egyptian team will be directly affected if Salah is absent. As for Liverpool, their schedule this January is not too heavy, they only have to play one match in the Premier League against Bournemouth.
That's why Liverpool can completely give Salah the right to rest in the next few weeks if he is unfortunately injured. The Premier League championship race still has a long way to go. This is just a temporary shortfall for Liverpool. Mancity should not be too hasty to rejoice and lose focus.
The news about the gravity of the hamstring injury might be out today after a proper medical checkup. Both Egypt and Liverpool will be hoping that that injury is not that serious. His absence will have some negative impact on the Pharaohs as we saw the Ghanaian fans cheering when they saw that he was injured. Everyone knows that Salah is a threat to any defense. Liverpool will want him back as soon as possible to get the best medical treatment because they need the striker to fight for all the competitions they intend to win this season.
Liverpool and Manchester City will be very difficult opponents to beat, so Arsenal will have to work well as a team to get the win.
Arsenal need a run of victories to get themselves feeling like title contenders again, their morale has dropped a little but it is still early enough to fix things. The thing is, the level of competition in the EPL is elite and the top teams have to be at their best to compete for the title, Arsenal definitely know this from their experience last season and how they failed to keep up with the pace of City at the top and in the end failed to win the title after leading the standings for so long. Liverpool and City might turn it into a two horse race if Arsenal don't wake up, and it'd be another disappointing season for the Gunners.
Aston Villa has become more competitive than Arsenal in recent times. The Gunners have won just one game in five games while Villa have won two. Until Arsenal puts in more effort to win more games teams like Chelsea might overtake them if the latter puts more effort. Mikel Arteta will have to do more to improve the team especially to move to the UCL quarterfinals.