Since I've probably been the person speaking most darkly about possibly dropping Oracle support over the past couple of years, let me make clear where I've been coming from.
I look at it as a resource issue, pure and simple. Those who claim to want Oracle support have not, in practice, been willing to either take it on or pay for others to do it. They've wanted a Free Ride, in many cases.
In fact, when I raised the issue in Madrid, a spokesperson from one of the universities using .LRN (not Heidelberg, not Sloan) said "well, we use Oracle because we have a site license, therefore it's FREE".
Well ... it's only free because a handful of us have continued to fix Oracle problems on our own time, unpaid.
I've taken the uncivil step of telling people I will no longer help test or fix Oracle releases unless I'm paid to do so. I'm not trying to be mean, just practical.
It sounds like that faced with Oracle support disappearing, at least a handful of folks in the community are willing to step forward and lend a hand. That's great. If supporting Oracle doesn't cost those of us who only use Postgres time and money, I doubt any of us will care if Oracle's supported.
BTW we have, in the .info file, the means to state "this package only supports Postgres" (or Oracle). That's not an issue. If someone extends a package for (say) PG and breaks Oracle, they should remove the db tag for oracle from the .info file. They should probably announce what they're doing so someone from the Oracle community can pick up and fix the package if they so choose (as Janine has chosen to do with project manager, for instance).
As far as comments like "I honestly don't know what the major stumbling blocks in efficiently maintaining support for both RDBMSs are, and I'd like to hear about them from someone who does."
Well, it should be clear that testing for two RDBMS's takes twice as long a testing for one RDBMS. Add to that the overhead of maintaining query files and the fact that there are really large differences in any hierarchical query (just one example) and you see that supporting both is non-trivial. Supporting both is probably about 35% harder than supporting one.
The need to do so is, in essence, a tax ... with the web development industry being much more competitive than it once was - $300/hr contracts appear to be a thing of the past - it's becoming harder and harder to pay that tax.
Folks might want to keep in mind that I (along with Ben Adida) was the originator of the notion of supporting both RDBMS's. Our support for OpenACS 4 began as a PG port only, but from almost the very day that aD announced they were dropping ACS Tcl our project announced we'd figure out a way to support Oracle as well as PG with our port of ACS 4.
And I did the hacking on the boostrap/installer, APM and other components that guaranteed that our first release of OpenACS 4 would support existing ACS 4 custom packages without any modification whatsoever.
I only point this out to make certain that folks who might be newer to the project understand that my wish to drop Oracle support is a huge turnaround in my original position.
Regarding Oracle and institutions/companies ... PG is making significant headway in that regard, as of course is MySQL. And SQL/Server for that matter ...
So I don't see it as being as huge a marketing advantage as it was six years ago. Large, yes, just not AS large.