Yep, Batshuyai would be a shrewd signing considering he is younger than Morata, would play in the same exact roles as him and his price is mostly covered with the Morata money. Add in Isla to sweeten the deal by 3-5mil and it's all good. He wouldn't be an old plug-in, but a signing for the future.
And even if he flops, his age, nationality and position would guarantee we would barely lose money if he has to be shipped after a bad season.