Have the online family tree programs progressed to the point that you no longer need to buy your own genealogical database program? Can you now keep all your records online? The answer to both of these questions is a qualified no. The reason the no is qualified is because how you maintain your genealogical data depends entirely on how much and what type of documents and data you have accumulated.
For some people, starting and keeping a family tree online may be all they expect or require from their genealogical experience. This is especially true if the person's goal is merely to record the information for some purpose other than doing research. From my examination of hundreds of online family trees, it appears that whatever the motivation of those who posted the information, they are not intent on expanding the pool of information readily available online to copy and are content to remain blissfully ignorant of any additional facts about their particular family. At this level, an online family tree serves their purpose entirely.
But if you are interested in doing even a modicum of research, You will quickly exhaust the capabilities of nearly all the online hosts for family trees. There are a few online hosting organizations that have developed or are in the process of developing programs that are feature rich and have the capability of storing all of the data, including notes, photos, documents and other items, most people could hope to generate. In those cases, and again depending on the needs and expectations of the user, this type of online program just might act as a substitute for a local genealogical database.
Here is the problem. Even if you use an online host for your genealogical information, what happens if that online host goes out of business, raises their rates substantially or takes some other detrimental action? What happens to your data? Recognizing this and the additional fact that you may not want to share all of your information online, there is a definite need for local storage and organization.
Unfortunately, I find a significant amount of resistance to the idea of having your own genealogy program. Its not that the people have all their data online, they simply do not see the need for recording their family history in other than handwritten forms, spreadsheets and databases. They most certainly do not see the utility of paying for a program especially if the program is going to require periodic updates. Even if they see the need for a localized genealogical database, they seek out programs that are "free" or otherwise have no significant cost.
Will the online programs get to the point where it is meaningless to try to maintain your own personal program? What I see as more likely, is the evolution of the combination of a local program and an online version of the data. There are a few of these programs already such as Ancestry.com's Family Tree Maker and MyHeritage.com's Family Tree Builder. As these dual, online and personal programs become more sophisticated, I would guess that more and more of the genealogical community will begin using these or a variation of the programs. There were several of the FamilySearch.com Affiliate programs that would exchange data with the New.FamilySearch.org program, and while that was seen as an advantage by some, others who had already submitted their data to FamilySearch were appalled at the way the conflicting submissions were unresolved. Presently, FamilySearch is developing Family Tree to resolve some of those problems but has yet not allowed third-party public access to the Family Tree program except in some limited areas.
In my opinion, there is presently and will be for the foreseeable future, a need for your own dedicated genealogical database program if for no other reason than to preserve your own research and opinions concerning your ancestors. Eventually, given an increase in the capabilities of the programs, there may be some viable alternative.