I have 3 questions about your space, Do you want external access for laundry to back yard? Is there a window/external door in there? Could the bath be just a nice galvanised tub/large plastic tub/baby bath that hangs on the wall until needed? (Filling & emptying it happen in the new shower with flexible spray arm???) My first thoughts are to keep all the plumbing across back wall (if no door planned) and move the entry door to the linen cupboard on right hand side. Then make linen cupboard on left front wall and accessible in part from both sides ie. bulk towels etc outside upper wall access (behind shower) then laundry basket & other storage is inside access, How about a modern shower which is 13-1400 mm square (same position as current layout) with a 7-800 mm glass door on left and a tiled 600 mm blade wall on the back right hand side which the laundry stone bench butts to (window over?) Leaves 18-1900 mm length on back wall to accommodate the tub/sink and washer dryer. If you place the washer/dryer under the bench and a 500 mm wide storage cupboard you gain a greater bench area for sorting etc and wall space depending on window for shelves, hanging rack etc. If you really want a bath Decina have a corner model and a rectangular to fit these dimensions and then you would need a shower screen (will this be the only bath?) With the door into this room on the right it creates the better flow straight ahead to the laundry and left with some privacy to the shower/bath. The linen cupboard is a good size and you could have a hatch on the outside right to the laundry basket inside which could even be on wheels in a recess/niche. Hope this makes sense and helps a little. :-)

Our house is full of cavity sliders. Twice they were all (but one) replaced due to swelling/warping and rubbing against framework when opening and closing. Some made terrible noise whenever we opened or closed them. Hubby had a hunch they were poorly manufactured overseas and discovered that was the case. Builder sourced a local manufacturer and the whole lot, bar one, was replaced and we haven't had any further issues. The one door couldn't be replaced due to it's location - a wall would have had to be pulled down, just as co-design has described. This experience makes me think it may be a case of ensuring you purchase well manufactured doors for your climate and particular environment, and take into careful consideration the particular location they will be installed.

This with the extra width you suggested the built in bath with a large shower space next to, the shower head coming off the opposite wall to help avoid water to window, the window would be best tiled, the wall with the shower door into "The wet room could be all glass up to the vanity. There are several suitable places for towel hanging and an extra storage cabinet could be above the toilet, I forgot to add this

if the goal is to make a more spacious WIR my suggestion has a HIS and HERS arrangement with more than 3m of extra storage wall, more standing/dressing space and a brighter daylit room and there's the separate toilet, double shower and generous linen storage and, although it's shorter, the vanity bench is still over 2m wide with matching mirror doored wall cabinets but there's also and out of the way standing space next to the shower that doesn't have a wet floor or block access to the toilet ..i've included a copy of the original and new plans for comparison