Average life of the Z10

I got my Z10 last April when it was launched in our country. I was wondering what is the lifespan of the Z10 as I noticed that newer phones last shorter compared to that of the older models. My first phone the Nokia 7110 lasted me 5 good solid years. My Nokia 6230 lasted 4 years and my Nokia E66 lasted only 3 years. My curve 9360 lasted me less than 2 years and now I think my Z10 is starting to show signs of wear. I shudder at the thought of the trend in my phone usage.

Sometimes my lock screen switches off on its own after a few seconds despite my setting it to 5 minutes. My signal is very erratic that I sometimes lose signal despite having good area coverage. This is clearly a phone issue since I put my sim into another phone and the signal is great. Although my battery life seems to have improved over the months. Overall, I think my Z10 is starting to show its age. As much as I want to replace my Z10 with the Z30, practicality is a big factor for me. My carrier will no longer honor returns as my warranty is limited to two months. And funny thing is, despite getting my Z10 from a carrier, it is unlocked. I tried using a sim card from a competitor network and it works.

I want to continue using BB10 since I like the way it flows. I've tried android and ios and I find it cumbersome especially for multitasking.
BB10 really suits my needs.

Again, how long do you think the Z10 will last? Any thoughts on this?