The day you can submit a paper without any revisions from your advisor, you'll get your PhD

I am an undergraduate student in Asia and my advisor ( for my Bachelor's thesis) is from a university in the US. I worked in the US under him for one semester, where our research produced some significant results. Just before returning home, I was told that we would submit our work to a journal 'pretty soon'. Now that I am back, my advisor has suddenly assigned me a LOT of new work in the same direction, saying that 'it is necessary for a good paper'.
I suspect that my advisor is deliberately adding to my work and delaying publication so that at the end of my undergraduate years, I return to him for my PhD.
On the other hand,if I do get a publication now, I'll have higher chances of acceptance at other good universities, and I'll have a choice of universities to apply to my PhD. It makes sense to me that my advisor will prefer to have the work unpublished until I come to him as a graduate student (In a way, I shall be trapped).
How real are my suspicions?