Isn't Kate Walsh busy with the second season of Netflix's 13 Reasons Why, though? Plus, she's played the ex-wife who shows up in the very last scene of S1 on Grey's Anatomy already, and let's not forget Grant Show played her brother on Private Practice. That would make it a little awkward to watch to me, just like Melinda Clarke, who I absolutely love, would take some adjusting due to the fact that her character on The OC married Alan Dale's, so it would feel like Alexis used to fool around with Joseph to me. XD
As far as Tori Spelling is concerned, I am currently watching Beverly Hills, 90210 on DVD (just started S7) and I am far more intrigued by her inability to find a hair color/make up combo that works for her than by what she has the nerve to call acting. And again with the previous roles thing, it would just feel like Donna Martin had two kids with Jake Hanson to me. It was hard enough to adjust to Brian Cunningham/David Silver making out with Victoria Broyard/Kimberly Shaw on Desperate Housewives! XD