Ninty (and many of their 3rd party's) stepped in and is taking action against retailers in Japan that sell R4-like devices. That is all. So unless you live in Japan, no worries as of now.
But yes, apparently the R4 is now an obsolete card that will receive no more updates. There are rumors that there will be an update on Sept. 15 specifically designed to brick clones and fakes of the R4 (and possibly your DS too), but I believe that to be pure BS.....we shall see.
Personally, I bought a CycloDS to replace my R4 (which still works).
The most recommended replacements are: SCDS1, CycloDS, AceKard RPG and Edge. I think you can guess which one I'd recommend, but the choice is yours as to which one you go for.
EDIT: Sorry JPH, no witty R4 bashing from me today.