You don't measure investment in just dollars spent or earned. If something is a hobby then personal enjoyment is far more important. If that hobby is expensive, and Trainz is not expensive, then you moderate or "ration" your involvement but still find ways to enjoy it. There are plenty of people on modest incomes who find and restore old cars not for the financial returns but for the enjoyment. Many of them could not even begin to tell you how much money, time and effort they have invested.
You can find plenty of examples of high quality routes on the DLS that are as good or better than those on the DLC. I recently bought "Coal Country" and find it a very well crafted route but I do question some of the choices the creators made (billboard trees, non-procedural tracks, etc). These choices may have been made for commercial reasons (faster development time, ability to run on low end computers, etc) to maximize their market return. Those are choices that freeware creators are not required to make but their investment in time and effort can often be far greater.
Some freeware routes have taken years of time investment. How do you quantify that in dollar terms?
Out of all the hobbies I have "invested heavily in", Trainz is the least expensive even with countless DLC, Jointed Rail routes and content, and other third-party content, and this doesn't include the time investment put in for testing routes and beta testing Trainz versions over the past 14 years of using the program. If I were a fulltime employee, I would have been paid aplenty for my time in the program, but being a time waster, as some people refer to hobbies as, it's for the fun of it.
If people were to see what I've spent over the years on severe storm chasing at 30K in travel expenses, and my keyboard instruments have run about the same at 30K, not counting countless lessons and even a year in college towards a BA in Music, they'd have me put in the nuthouse with a straight jacket decades ago. But if it wasn't for hobbies, which I think define our being and allow us to express ourselves and escape from life, we'd also all be in the nuthouse since hobbies take our minds away from the horrible world we live in, as well as help us face every day with strength and determination needed to get through the weeks and days, and give us something else to look forward to beside work and chores.
Anyway back to the original statement by the OP, which we've strayed some distance from, I still feel that this program would be relegated to the likes of Softpedia with older out-of-date programs with no support and no development. Without the financial backing and research, we wouldn't even have what we have today in T:ANE as much as people knock it. With continued financial support, the developers are making some rather interesting progress with the new graphics capabilities, which will make T:ANE and Trainz in general a far more superior product.
We do, however, have to keep in mind that this new technology comes at a price in terms of hardware requirements and software complexity, but given the right hardware and with proper tools, there's no reason why people can't learn to make use of the new stuff once it's available. Like all versions of Trainz, I am sure there will be that backwards compatibility there which will allow earlier assets to be used, however, like all older assets they won't be able to make use of the newer technology without rework by the authors.
The future of Trainz, to some of us, is a painful one. We're all tired of repairing content which we've had installed for years without errors only to find the next version brings up errors which were unknown to us and want all our content from 10 years ago, and even 15 years ago, to look perfect and work the same without errors as the new content does. The stricter error checking has come a long way to make the program more reliable, and it will still have an even longer way to go to make it even more reliable as time goes on. This doesn't mean the program is not without its share of bugs, but as I've said before compared to some really expensive business software, found in corporations, this program does is a lot more stable with far less support.
Do we let go all those assets we've gathered over the years, and move forward, or do we continue to repair and hope our old stuff still works? The choice is ours here, and as a community we have shaped what Trainz does more than we think. If we are truly concerned about lack of new assets, we should all, including myself, take up the gauntlet and start creating assets for the newer version just as the original Trainz pioneers did over 15 years ago.