In addition or replacing some of the A330?

I would expect that some A333 will be replaced - a new A359 full of paying pax is probably cheaper than an old A333 with a ton of lead in the back.

You are right. Aerotelegraph reports that they will replace the oldest A330s.

An A330 is smaller though... not every destination LX flies to can take the capacity of an A359. LX learned that the hard way when deploying B77W on former A343 routes. A written off A330 still produces a cheaper seat.

A333 current 8F 45C 183Y
A333 nonSense 3.5F 43C 21G 159Y 1000Pb
A359 nonSense 3.5F 45C 38G 156Y

Not that big a difference and Premium Economy is the largest profit generator in terms of $/m2.

Oh joy!
I suppose the one saving grace will be that by the time all those planes are produced and Senseless is installed could be many years away. And the routes I most often fly are likely low down in the priority list for NonSensification.

Additional fun thing is that they were incapable of creating a proper premium economy cabin in this new shebang, devaluing the already high price difference between the cabins

The A330's were delivered between 2009 and 2013. When it comes to age the oldest plane will be less than 20 years in 2027. Looking at the delays with Senseless + the extra weight that would need to be added to install the cabin it would be best to scrap the idea to upgrade the A330's and replace them sooner than later. How it looks now this at least seems to happen partially and if at all only some of the frames will get the seneless upgrade and be in the fleet until approx 2033-2035 until replaced by A350's unless they will get more frames allocated from existing orders of the group.

As it was done in the past we will sure see additional top up orders. In order to replace the original 5 A340's + the 14 A330's at least 19 planes are needed. Looking at delivery delays not sure if LX could get all 19 planes by 2031

I could imagine the follwing scenario to happen to keep the upgrade costs and damage as low as possible with the whole senseless planing but doing something about the A333 cabin:
1. Keep the 4 A340's in the fleet for the timebeing and use the first 5 A350's to replace A330's.
2. Install Seneless on max 9 A330's between 2025 until 2027 and replace the A340's between 2027 and 2031. From 2031 onwards replace the remining A330's. Not to forget additional aircraft capacity is needed from 2027-2030 +- to compensate missing B77W's that will also get the seneless upgrade.

Some LH/LX A330s will go to 4Y and SN. The extra weight story is a nice joke, but over all the switch to the new cabin will result in an overall weight reduction. The weights in the tail are required due to the dramatic reduction in weight in the PE/Y cabin and the galleys. Materials have evolved over time and seat construction has become much lighter since 2008-09 when the A330 was specified.

I'm scratching my head off : everything is sooooo Senseless, Now they come up with a PY cabin with just 1.5 row of Y ???? Couldn't they simply add a PY row and call it a real cabin with dedicated bathroom ?? (too much to ask?)
They are really trying hard to make everthing so complicated.
But surely LH teams have had a wonderfull idea to create a Y "luxury row" and market and price it accordingly... Probably at least 27C and 27H will bring a few extra bucks to the financial results, congratulations for such a well designed product - 26B and 26J will be thrilled to seat next to their back neighbour's feet !

That one row of Y is silly but I don�t think you can suggest to dedicate 4 lavs to Premium Y and leave Y with the 5th one in the back? To create a dedicated lav the whole layout needs to change. Maybe that�s work in progress, or is that too much wishful thinking?

Adding extra weight is a Joke ??? since when ?

Since they decided to use lighter cutlery in order to reduce weight ao that they can save fuel

Very silly indeed ! They could have dedicated 1 lav to PY with a curtain thing of sort (without that stupuid Y row obviously) and leave the other 4 lavs to Y.
Howcome is there so few lavs in this plane ? I wonder how it compares to other A350 layouts of other companies ?

I am surprised they are not downgrading Fat pax to the last rows of whY