Scared to Change it

Ok, I have 7yr old domain which has ranked in the top 3 since its
existence, due to strong backlinks.

When i set the domain up, competition was very weak but not now.

Domain still ranks in the Top 3. I know now is the time to change strategy.
The thing is, I am very reluctant to change "a good thing". I would hate
to see additional content making the site sink.

I am thinking of adding additional content.

What should I do - change now OR leave it be?

 

Just leave it, only change it when you found your traffic is dropping

 

If you said your rankings are due to strong backlinks then a content change won't due much harm. Do it if it hurts your current conversion rates - long-term you can't stick to whatever you currently have on the website if it has lost relevance to your visitos

 

If you're still in the top 3, why change anything?

 

I'd leave it but adding additional content certainly won't hurt it.

 

Don't change it instantly, maybe you can do some trial on your other site or some of your inner pages.