How well prepared are TCI/TPRS students?

This is my first year of teaching with TCI/TPRS.  I haven't had much training, just personal interested and I've attended two short workshops.  I'm currently sitting at my 3rd workshop in Maine with amazing teachers such as Carrie Toth, Laurie Clarcq, Anne Matava, Sabrina Janczak, and more!  It's been an awesome 2 days, and I am feeling very refreshed and enthused about TCI.  I'm feeling more confident.

But I am fighting an internal battle.  I've taught with a textbook for 12 years.  In the past few years, since jumping on twitter and following creative, enthusiastic teachers, I've grown in my thoughts and beliefs. I very much dislike the textbook style teaching, but I'm not sure how to change.  How can I change my class, if the kids are going on to the next teacher who expects them to know ALL of the vocab, grammar, etc. from the text?  Slowly, I've tried a TCI lesson here or there.

Then, I happened upon a great opportunity.  My district would be making 2 years of a Foreign Language a high school graduation requirement.  Beginning with this year's freshmen, the class of 2018, all students must take 2 consecutive years in order to graduate.  My department talked about a special course, with only 2 levels, aimed at students who struggle to learn in the traditional textbook/grammar driven classroom.  That's about the time I started really hearing and reading about TCI/TPRS.  Fast forward to this year- I am currently teaching 12 students, 9 on IEPs (Individualized Education Plans) mainly for language based disabilities, some for behavior, attention, etc.  This course was listed in our program of studies as Spanish Language and Culture 1 and 2, with a description based on TCI/TPRS, music, novels, videos, etc.  It was supposed to be a slow moving pace, with reluctant, or struggling learners.  

My district purchased 3 novels from TPRSPublishing, and a teacher edition of Cuentame Mas, so I could use the TCI/TPRS approach in this "special" class.  

I started the year with a unit I created based on 3 structures (tiene, quiere, hay), and then jumped into the Cuentame Mas text.  So far so good! I am still getting my feet wet, but the more I play around with it, the more I find it to be a natural way to acquire language. My students impress me every day with their thirst for more Spanish! They always try to answer in Spanish, using our current structures, or drawing back on things we've already learned!  It is amazing to me, these students who supposedly "can't learn a foreign language" are reading, listening, writing, and speaking in Spanish!! It may be limited right now, but it is more than they could do September 1!

My only concern would be what would it be like for these students to move on to another teacher next year, in a textbook driven class?  Would they lose their thirst for Spanish? Would they become lost and never catch up? I hope we don't have to find out.  I hope I can convince the other teachers in my department to implement TCI/TPRS and we can create a community of students who WANT to learn another language, and graduate as young adults, capable of communicating with native speakers.