Think of it this way. If a technology is out there that is out selling another tech (say LCD vs Plasma), companies who produce both (for example Samsung), at some point will think that it makes financial sense to put all their R+D budget into LCD. There will also be companies like Sony, for example, who dont do plasmas at all because it doesnt make financial sense. All their R+D budget is spent on LCD.
Consider that those are just 2 companies. Now consider all the other smaller, more obscure companies out there. All their R+D budgets will be invested in technolgies that will sell high and allow them to make greater profits. Hence, given that LCDs outsell plasma and are continuing to gain momentum, it makes sense that if you look at the entire worldwide R+D budget of LCD vs the entire world R+D budget of plasma, you will find that LCD is destined to improve at a faster rate than plasma and eventually take over, in terms of picture quality.
Of course, there will always be a niche market, should sales drop to miniscule levels, for plasmas, but I just feel that LCDs will offer better value for money, at some stage in the near future, due to the huge R+D budgets.
Right now, what is keeping plasma in the game is that it offers better image quality than LCD, for a given price point and size. And even then LCD outsells plasma. What do you think will happen to plasma sales, once, for a given pricepoint and size, an LCD screen is able to deliver better images than plasma?