Here is the only yearly data that I could find:

http://www.w3schools.com/browsers/browsers_stats.asp

You could certainly read that to mean that Opera has doubled its market share since early 2003.

You could also read that to mean that Opera has remained at about 2% market share for six years now, during which time Firefox has been born and risen to about 40% penetration, and during the last six months of which Google's browser has been both released and passed them by a factor of 3.

So yes, Opera is not going anywhere. You can read that to mean that they're going to stick around if you'd like. You can also read that to mean that they are not now, nor have they ever been a real competitor in the Browser market.

I don't know if those statistics are really that accurate. They are often biased towards the desktop/laptop, & often the USA/English as well. Also from that Wikipedia article:

As of September 2008, usage data on English-language sites show Opera's share of the browser market as being below 1%. The browser has seen more success in Europe, including about 18–20% market share in Russia and Ukraine,and 5–6% in Poland, Latvia, Lithuania, and the Czech Republic.

Unlike any of the other browsers listed in those statistics, Opera is developed by a company based in a non-English language country. They have their own niche languages/platforms and I'm sure they're doing quite well in them.

That said, I live in the US and find Opera to be entirely usable on my laptop. In fact, I asked on another thread (http://news.ycombinator.com/item?id=622038) why Opera doesn't have a larger market share, and most of the reasons given were non-technical.