Why aren't you bilingual?

It's been a while since I've had time to leisurely think and write for my own pleasure. My little one turns two this month, so the timing is right as she boldly displays her independence with each passing month! She is speaking Spanish and appears to understand everything said to her in Spanish. My oldest just turned five and she is completely bilingual. My heart swells just thinking about it. It is beyond a doubt my greatest accomplishment in life - one that could not have happened so easily without my husband who also instills in them the importance of maintaining a connection to their Colombian roots. I know many families like ours - parents from different countries with children learning the best of both - both cultures and both languages. I also know the outcome varies greatly. It's a challenge to consistently maintain the target language especially when the kids go to school and none of their friends are speaking that language. Push-back can happen and all you can do as the "language parent" is to continue speaking & continue asking for a response in the target language. It can be an uphill battle because a parent must also be careful in not creating a hostility toward the target language. We as adults know though that anything worth doing is typically not easy.
So, here I am with one bilingual and one speaking only Spanish (for the time being). It's amazing to watch it unfold. As a linguist I take note of every detail that comes out of their mouths. The oldest learned English mostly from going to preschool, watching Nick Jr. shows, and grandparents. Her Spanish vocabulary is bigger and so she inserts Spanish words into her English sentences - mostly during the school setting. "I have a morado." ("I have a bruise.") Not knowing certain words in English - she just substitutes it for the Spanish. She also speaks English using Spanish structure - "I'm going to the house of Grandma." Instead of "I'm going to Grandma's house." I'm not concerned about these nuances at all - I believe it will all come out in the wash, but I can only imagine what her little friends (& teachers!) are thinking when she converses.
In Spanish, she converses freely in the past modes (Preterite & Imperfect) and in the subjunctive. These are things that take my students MONTHS to even understand. "Papi, yo sabía que te gustaba eso." - she says in her sweet little voice. Now that I'm five years in this process of bringing up children as bilinguals, I understand to my core that this country is going about the foreign language experience in the classroom all WRONG. No student should begin a language for the first time as a freshman in high school. Nothing about their brain development supports this. K-5 education should incorporate foreign language as a CORE course - not an elective or enrichment, but a core where they have at least five hours a week in the target language. The United States will always be behind on an international scale until we make this a priority and change the way it's done across the country. The evidence of the benefits of children learning a foreign language at an early age is now overwhelming. As our nation's cultural landscape changes - the question will also change from "You don't happen to speak a foreign language, do you?" to "Why don't you speak Spanish?"
Those on the "We-speak-English-in-America" bandwagon should look at it from a more global perspective. We are one of few countries where kids graduate from high school and students can not function in another language. It's appalling and almost ethnocentric. Not too long ago French was the lingua franca and then it changed to English. It will change again; and when the English-dominant era declines, who will be prepared?

In the United States, it is projected that the Hispanic population will double by 2030 & triple by the year 2050 making "White people a minority," according to the Huffington Post.
It is also speculated (by scholarly sources) that Mandarin Chinese or French (again) could become the new lingua franca. Only time will tell, but in the mean time, I will continue preaching about the importance of being bilingual.

UPDATE - JULY 2015 - El Instituto Cervantes published an article stating the United States is now the world's 2nd largest Spanish-speaking nation!! That is huge! This means that only Mexico has more Spanish-speaking people than the United States. Times are changing and being able to order a taco or find the restroom may not cut it by the time our children are in the workforce.