Lots of options. It already has what you need so just a reconfigure. The master ensuite is way to small. Could move master to living dining. Now you can open up rest of space how you want

And maybe move front door to right

The house is detached from the back yard because it is on a different level. I would extend a deck out into yard, then steps down to yard. Dining becomes bedroom, so bedrooms are all grouped together. Living become new ensuite and master bedroom. Open up walls on all rooms on the right. Obviously there will be load bearing walls, so you may need to keep part of walls. A good architect can make them a feature. The front is north, so having the living, kitchen and dining opened up to the front would be beneficial. Then flowing onto the new deck into your yard. The second living would stay as the rumpus room. But, what is the house made of? Internal bricks or timber. What are the floors made of? Concrete or timber. What is your budget? Yes there is potential to change floor plan, but does your budget equal the expense?

Example of support pillars incorporated into design.

Some layout opts