The SPL became even more interesting after Cristiano joined Al-Nassr, and now, Karim Benzema has also followed in Cristiano footsteps and joined this season SPL winners Al-Ittihad. Of course, the arrival of big stars will change the way the world views the SPL and will also change the atmosphere in the league itself.
Indeed. The next season will be interesting since both Benzema and Ronaldo are in different clubs. So, they will be rivals, which one to be the best striker in the next season. However, if there is no significant change both in Al Nassr and Al Ittihad, I think Benzema will have a bigger chance to be the top scorer. Al Ittihad looks stronger, especially since they have Benzema for the next season. SPL atmosphere may be as well as the top league in Europe for the next season. 
BTW, there are no more rumors about Messi joining Barcelona or any of the clubs in the SPL, officially he will play with Inter Miami, this is a shame for the public because if he joins a Saudi club, we'll see their rivalry (Cristiano & Messi) back before they actually retired.
Yes, the latest news I heard that Messi finally decided to join Inter Miami. It will be very surprising if he canceled the decision and choose one of Saudi clubs.