Can I, as an adult, learn a second language as good as a child?

Did you know that our brain is plastic? 

Well, it doesn't mean our brain made of plastic, though. Neuroplasticity or brain plasticity refers to the brain's ability to change throughout life. The brain has the amazing ability to reorganize itself by forming new connections between brain cells (neuron).
 It is AMAZING! 
In addi­tion to genetic fac­tors, the envi­ron­ment in which a per­son lives, as well as the actions of that per­son, play a role in plasticity.
Neu­ro­plas­tic­ity occurs in the brain:

1. At the begin­ning of life: when the imma­ture brain orga­nizes itself.
2. In case of brain injury: to com­pen­sate for lost func­tions or max­i­mize remain­ing functions.
3. Through adult­hood: when­ever some­thing new is learned and memorized

Plas­tic­ity, learn­ing and memory
For a long time, it was believed that as we aged, the con­nec­tions in the brain became fixed. Research has shown that in fact the brain never stops chang­ing through learn­ing. Plas­tic­ity is the capac­ity of the brain to change with learn­ing. Changes asso­ci­ated with learn­ing occur mostly at the level of the con­nec­tions between neu­rons. New con­nec­tions can form and the inter­nal struc­ture of the exist­ing synapses can change.
Did you know that when you become an expert in a spe­cific domain, the areas in your brain that deal with this type of skill will grow?
For instance, Mr. A, 38 years old, is a native Indonesia. He started to learn English when he was 13 (middle school age). Currently, he works in multinational oil company, where he needs English a lot. He's realized that oftentimes he lose such opportunities to get ahead in his company, compared to his peers Engineer with  better English skills. Yeah, it is a matter in rivalry world, otherwise you will be left behind. Later on, he takes up some English courses with the hope that he will improve his English skills.
My question is, do you think Mr. A will improve his English skills?
Some of you say "yes" and I hear some of you say "hard to say "yes".
I personally believe that "yes", Mr. A will improve his English skills. Why not? I mentioned above that, "Research has shown that in fact the brain never stops chang­ing through learn­ing". I believe, this changing is not only happen to children but adults also. Of course, you can not compare children's brain plasticity to adults', but if adult do learning  regularly with good learning strategy, I firmly believe that adult can reach same second language fluency as children have.
So, don't you ever say this, "I'm too late to learn". Always, never too late to learn something. God has blessed human with amazing brain that can receive many new things and store it in our brain. Do you want to fully use your brain? Or just keep it original and useless? Life is a choice! Cheer!!

 Keep learning for your rainy days!