Yes, this is certainly possible, as the link to the openSUSE wiki page you linked to explains in detail. Also some vendors do this, e.g. the google-chrome RPM package for Fedora/openSUSE (also works well on other rpm distros) is one example where they only have one rpm package which covers the major rpm distributions.
But you should pay attention to what you require. You have to distinguish between
Requires: on normal packages for e.g. binaries that you might require. Those have to be manually added. Also Requires on filenames (e.g.
Requires: /usr/bin/sendmail) are disregarded and they're also not portable, as some distros will put their files in slightly different locations.
Requires: on common library packages, those are usually always wrong. They are automatically added during rpm build time. There are really rare cases where a certain version needs to be enforced, and where explicit versionned Requires have to be added, mostly on library packages. This is explained e.g. at http://fedoraproject.org/wiki/Packaging:Guidelines#Explicit_Requires