Since I am working in Vignette CMS domain from the past two years, I would say it has bright future ahead. The industries like News, Media, Communications mostly uses commercial CMS products. SMBs also use some open source CMS products like Joomla, OpenCMS etc. Just like banking, insurance etc. content management is also a nice area to explore and grow.
Sai Surya, SCJP 5.0, SCWCD 5.0, IBM 833 834
http://sai-surya-talk.blogspot.com, I believe in Murphy's law.
Since you asked this in the "Jobs Discussion" forum, I'd like to point out that banking on the future of any one particular product is a bad career move. CMSes will be around for a long time; whether Documentum will, too, or whether you will be able to make a living with Documentum (or any other particular CMS) is an entirely different question.
It's just about impossible to predict where a field as fast-paced as IT will be in 5 years (or what you will be doing within that field in 5 years time, for that matter). Keep up with technologies, be prepared to learn new things (including programming languages - Java isn't the be-all and end-all of that), and you'll be fine.
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