OpenOffice.org is one of the flagships of desktop installations of GNU/Linux. It is one of the most active projects in FLOSS. At 450000 it almost certainly has the largest community and possibly installed base (GNU/Linux or FireFox may be ahead in numbers…).
The featureset and ease of use of OpenOffice.org are mature and first-rate. With such a large community of supporters and installations, it should be around for a long time. The question arises about how acquisition by Oracle might affect it in the future. While Oracle has a lot of influence, the project is open and a larger base of contributors do operate. A recent article questions the intentions of Oracle for this product because on that other OS dependencies on non-free software exist (Visual Basic). The same doubts could be raised about several other projects Oracle acquired from Sun: MySQL and Java being the most prominent. VirtualBox is important and has no clear alternative as a GUI. The recent suit against Google for patent violations is alarming. FLOSS needs to be above that fray to stay healthy. If the owner of a project is willing to sue other members of the community using software fairly (an assumption) FLOSS will fizzle. Such actions essentially renounce Free Software status.
On the other hand, these major projects including OpenOffice.org have no clear alternative except forks and the patent-sword can still be wielded against the forks or alternatives. Postgresql and MUMPS ( non-SQL/RDBMS) could be used but a patent-troll can still attack on the basis of functionality. With OpenOffice.org that is true as well but most of the technology of office-suites is long standing and not subject to patents. The exception could be Java. The database component of OpenOffice.org depends on Java. It could be replaced by a dependence on Python or other scripting/interpreted language but that would be a major disruption.
I do use alternatives of OpenOffice.org from time to time. KDE Office and some components of GNOME work (GNOME also depends on OpenOffice.org). I use LyX for some writing projects. KWord includes the database-merge capability so useful for writing students’ reports. Everything else in OpenOffice.org, I have good substitutes like GNUmeric, phpMyAdmin, Scribus, Inkscap, Dia, etc. but they are not so well integrated. Could we survive a catastrophe with OpenOffice.org? Yes, but it would be a major disruption. In order to minimize disruption it is important to explore options long before a crisis emerges. I have frequent opportunities in my teaching but others will have to make a determined effort to explore GNU/Linux for functionality outside of OpenOffice.org.
Oracle still sells StarOffice, officially so they may continue that and leave OpenOffice.org alone one way or another. We shall see in good time.