Not a good idea in my case. I won't get my iOS updates without a computer. I won't be able to do heavy processing (scan receipts, handouts, pamphlets, articles, etc.), run optical character recognition on pdfs, view websites with funky formatting, upload files to sites, etc. I won't even be able to use full-featured word processors like Microsoft Word or Scrivener.
I can go for days or weeks without a computer, but forever? No. I love my MBP, but if I wanted to, I would be fine with a sub-300 netbook. So, for under 800 you can get everything you need.