tssva is correct, most states have matriculation agreements between the CC system and state college system. So, at worst, you finish your degree at your home states flagship state university (obviously, those vary, but generally, each state has at least one well respected institution). If you're in VA, you "hit the jackpot" and have many choices (UVA, W&M, VT, plus a half-dozen other solid choices).
Locally (VA), students are guaranteed admission to the state university system if they meet a published GPA threshold. That threshold varies by school. The one big caveat - students are not guaranteed placement within specific programs. So, at GMU, an overall GPA of 2.85 is required to transfer, however that is might not be high enough to guarantee placement in their Computer Science program (which is highly competitive and close to fully enrolled).
I don't know how this applies to transferring to an Ivy (or other top-tier private). For the Ivies, I assume the caliber of student who can gain admission is going to figure out the finances (for better or worse). I also assume (big assumption here) that even a "useless" liberal arts degree from Harvard makes one employable at a reasonable salary (vs the same degree from a 2-tier school).
Edit - one "local" private school (Shepherd U, WV) also has a guaranteed transfer program from the local (Northern VA) CC system. They offer a tuition discount to those transfers. http://www.shepherd.edu/nova-transfer-admissions/