Examine the benefits to see if they are real benefits
The main argument for DNG seems to be it is a open format, so it is more likely that software will support it rather than proprietary RAW formats. But I don't find this compelling.
Firstly, has any software vendor actually dropped support for any proprietary RAW formats yet? So far, they like adding more and more features rather than removing any.
Secondly, you can always convert the RAWs to DNG in the future when/if the software stops supporting RAW. The RAW to DNG converter will not suddenly stop working, leaving you with RAW files you can't convert. Not to mention the software you currently use (assuming you don't update it) should still keep working with those RAW files.
If that day ever comes, converting your entire library will take a lot of time. But no more time than you would have otherwise used if you converted them incrementally. In fact, it might be quicker, since computers will be faster in the future. It seems a bad investment to pay for something that might never happen and if it does happen it might be worth less than what you put in.
Saving space is another argument, but only if you don't use the "embedding the RAW inside the DNG file" form of DNG and you permanently delete the RAW file after conversion. Is that something you are comfortable doing? The RAW file is the original source; the DNG file will always contain less than or equal information than the RAW file.