Yes the lounge access benefit ends on 31st December of the following year but that is not the same as it being tied to the programme year or status year.
The webpage clearly states it runs to the end of the year you select it until the end of the following year so yes you could have almost 2 years of lounge access if you chose your selection date wisely should your 90 day selection period cross into a new year an dyou wait until that happens.
The F&B and UPgrade benefits are one year from selection though.
But I've not seen anyting that indicates that the programme year will change to end on 28th February rather than 31st December other than the (rather odd to some) one off 2 month extension to status. to 28/2/23