Speaking a language perfectly, and speaking like a native are to me very different things. Speaking very well in a particular language without visiting a country is most certainly achievable, in fact I might even say preferable because the Internet nowadays makes it so much easier to find native speakers, and it is of course cheaper. But speaking like a native? If you move to the country as an adult, and not as a child then that is very, very tough and I would say an unrealistic goal, perhaps even impossible for the majority of people for one simple reason, the accent. For example even if you speak perfect English, with no mistakes in grammar or use of slang/expressions etc. it is extremely difficult to sound like a native because your native accent will give you away at some points when you talk. I have met many people who speak English very well having spoken it for many years, but even so a native speaker you can still tell that it is not their first language.

In my humble opinion, It's impossible, because every country has different emphasis, pronunciation, slangs of the same language. You just can not learn all of them sitting in your home. Of course, you can pass your IELTS exam on 8 - 8.5 without going abroad, but this score doesn't mean that you're real native speaker...

I have learned English since I was 8 years old. I had never been to any English speaking country until I was 21, but my language skills were advanced, and very close to a native level. Right now, after almost 4 more years, I can say I am fully native, and I believe that the full commitment and the interest I had in the language helped me mastering my English skills. I always loved watching TV shows and movies in English rather than Italian (the language I spoke since birth), singing songs in English, writing and talking to English speakers from all over the world. It's been a combination of many factors, but I managed to reach my goal :)

I haven't gotten there yet but I have a lot of friends who have. So my short answer is: yes! It's totally possible but it does require more commitment and willpower. If you're not living abroad you've got to find natives speakers to practice your language and that's not always easy, by living abroad you're surrounded by your target language, thus making things much easier. Anyway, it's just a matter of willpower, in my opinion.

of foreign language*