It doesn't. Preferred viewing is still an option for FP+ selections. Such things existed prior to the implementation of FP+ (albeit not as easily obtainable by the average guest) and they will continue to. With the Hub expansion I would expect an even larger FP+ viewing area for parades and fireworks in the near future at MK. These selections are always quite popular, they would have no reason to suddenly discontinue them.
This change only affects the proposed FP+ only character Meet & Greets which was honestly the most ridiculous idea ever.
"Let's make a FP+ only option for characters that can already be met in multiple locations throughout the parks, but also let's NOT put in a standby line. Not only that, but at parks where FP+ selections are split into tiers, let's make these options tier 1!" (Because I would totally love a FP to meet Minnie over RnRC or TSMM at Studios.)
And how exactly were they planning on explaining to guests who DIDN'T have a FP+ entitlement for those M&G locations why they couldn't go in for pictures when there wasn't a guest there to meet the characters?
"Sorry folks, you need a FP to meet Minnie."
"But there's no one here."
"Yes but you need a FP to meet them."
Yeah, then they go over to MK and wait at Pete's Silly Sideshow, which doesn't even offer FP+ to meet the same character with minimal wait.
Whatever genius thought up this gem to be their legacy hopefully got sacked.