Is there any way to retain my $20/mo iPhone 2G dataplan?

[elistan]

The iPhone 4S arriving tomorrow is going to replace my original iPhone 2G (yes, I've been using the same phone for over four years 🙂 .) When I pre-ordered from Apple, I selected the $30/mo unlimited because while I don't use much data on the 2G, I could see myself using a ton on the 4S. Unfortunately, that means I'm loosing my integrated 200 texts/month. Now I'm wondering, is there any way to keep the $20/mo unlimited data plus 200 texts plan when I activate my new 4S tomorrow? Or somehow use that to grandfather the old $5/mo texting plan for 200 texts? (At the least, I figure I'll go ahead with the $30/mo data plan and skip a texting plan in favor of iMessage, so no big deal if there isn't anything I can do to keep my old plan.)