As someone who has spent many hours hacking on open source software, I'm not sure I'd call it 'abundant' in that the production of said software is very much a costly endeavor. Once it's out there, yes, it's non-rivalrous, but that's a different thing.
Imagine the costs of getting a service oriented internet company up and running in a world where the only choice is Windows and IIS.
I wonder how much longer it would take sites like Youtube to scale to their current size.
So when PV prices fall to the bottom (trends indicate they will), electricity prices produced by PV will fall as well. Coal/Nuclear/etc will become unviable. What do we do then? Electricity will be basically free then.
In reality, what is happening is that because of "alternative" sources of energy, electricity is plentiful during the day, and scarce during the evening. Also, only turbines (hydro/thermo power plants) can be adjusted to keep current and voltage in the network constant, so we still need them, but because of the "green" sources, they are becoming less profitable for the operators.
TL;DR: alternative energy sources cause us to have too much electricity during the day and too little during the evening, both of which is costing us money.
If you produce energy, you get paid for it, but also pay a levy depending on how well your supply fits the demand. The levy goes to whoever fills in the gaps.
For example, the PJM interconnection holds an annual capacity auction. This essentially pays for the capital costs of keeping gas turbines around, at idle. The cost of actually running the turbines is covered by a separate daily auction for actual electricity production.
Liquid metal battery seems to offer some hope in this regard.
It won't be entirely free, but with enough effort, it might get very cheap.
Fresh clean water is much the same way. Water is so cheap, its market price doesn't reflect its value and you get companies pretty much wasting ridiculous amounts of it, which in turn causes problems.
I once lived in a condo suite with free heat and hot water. My showers were longer than they would've been had I been paying for each drop.
But I still believe the merits of abundance outweigh the demerits.
At the moment we already have plenty of people, but most of them aren't highly educated yet, and they need to spend all their time on stupid jobs that exist mostly because people need to have jobs. So more education and basic income could go a long way towards fixing this situation.
Once we can make "replicators" like in Star Trek, food will probably become free, too, but that's probably going to take another 100 years until nanotechnology is mature and cheap enough.
But these very people don't understand that they are currently enjoying one abundance right now: Free air.
The question is: How many things can we make as abundant as air?
OSS is there in fact. I would argue that electricity is next, then education (Khan Academy and the like), and one day fresh clean water.
We just have to keep knocking down one scarce resource at a time. The same way we don't take a single leap straight up the staircase, but instead take small steps to get to the top.