I've translated the comments from HSJ, Kisumai & 4TOPS here, because they were so touching. There were other Johnnys, but these are typically the ones I follow.
Nothing from Takki of course, as he's been very strict about not coming to the front at all, but an article did mention, he rushed to the hospital as well when Johnny-san was first hospitalized.
Rest in peace, Johnny-san. You've created an incredible empire of idols!