2013 Mazda 3-sport hatchback: Recommended Maintenance at 115k miles
 

I've had my Mazda 3 since new, now has about 115k miles. It's been very reliable, and I do routine maintenance (Oil Chnages, Tire Rotations), but have always avoided all the recommended upsell stuff like 30k and 60k maintenance packages. After some soul-searching, I've made the decision to keep this car, rather than sell for something newer. I've transitioned to a work from home job, and I also have an '07 MX-5 I drive sometimes, all of which means I get far less than 5k miles per year. So that's the background, question is below:

Knowing I plan to keep this car for a few more years, at least, I think I want to invest in some reasonable preventative maintenance. So far, I'm thinking of:

1. Flush and replace transmission fluid
2. Flush coolant, replace hoses
3. NOT replacing the timing chain (since they are not problematic on this car)

What do you all suggest I think about, given the reasons and background above? My general thought is "don't fix it if it isn't broken", sometimes opening up closed systems will cause more problems than they prevent.

What would you do? What are your qualifications to offer an opinion, and why to you suggest what you suggest?

#1 If you are going to get the transmission fluid replaced you will want to do a pan drop and filter change first.
#2 this sounds good but you do realize how many hoses there are actually on your MAZDA right? The better service is to drain and clean the cooling system and check the hoses and replace those that are showing signs of deterioration.
#3 Having a shop do a comprehensive vehicle inspection is well worth the investment . Then you will have a better idea what is needing to be serviced.