Yes, it's correct. For speakers who pronounce the /r/ in the standard way, it will blend together with a following /s/, even over word borders. There's a lot of variation in how r is said in different dialects so it doesn't happen for all speakers. Also, r:s don't blend when they're dropped altogether and if we speak extra slowly and clearly it might not happen either. So it isn't super important to make the 'sh'-like sound here.