In theory there's nothing wrong with your plan. In fact, it's not particularly novel -- plenty of folks have done, are doing, or intend to pursue a similar plan. So much so that "the south seas" are getting a bit crowded (at least, the anchorages anyway) in the opinion of many.
But in reality, "life is what happens when we make plans" (paraphrasing John Lennon). So my advice would be to focus on the short term objectives, and remain flexible with respect to the long-term goal. Think baby steps rather than giant leaps. Your "event horizon" is a long way off, and the best way to make your dreams come to fruition is to focus on near term objectives like improving your sailing and navigation skills, and developping a sound financial plan to fund your distant dream (for planning purposes, assume that it will cost you more than shoreside living/retirement).
We seem to get a lot of folks (many non-sailors) who show up here on their first post and announce grand plans to sail the world, so forgive me if my reply comes off a bit jaded. We often never hear from them again, too. So stick around, read and learn, ask questions. You may find a lot of helpful information here, and along the way on your journey you may decide that your plans need to be adjusted -- scaled back or, who knows, maybe enlarged!? No harm in that.
Welcome to SailNet!
P.S. You're in a great location to spend summers building experience aboard your starter boat. Many beautiful cruising grounds -- heading both north and south -- within easy distance of Boston. Here's a thread that talks about various daysail destinations: Link