The fact that more people are spending gold on high level gear upkeep rather than looms really makes no difference. If demand is high but there is not enough gold to be able to satisfy this demand, then prices will decrease naturally. There may be a bit of lag time but it will happen. As the game gets older, people will have retired more and loompoints will become more common. Therefore, supply will be increase and, unless the crpg community continues to grow indefinitely, demand will fall. This of course will result in lower and lower prices.
Conclusion: Sell now buy when looms are cheaper!!!
Another trend I've noticed recently is to do with the most popular weapons. Every now and again certain weapons or armours become super popular, sometimes because of a patch, sometimes for no apparent reason. Not long ago, the Danish Greatsword was the most sought after two hander and would easily go for upwards of 1.1 mil on the market. When weapons become popular like this, people become less willing to sell them and so potential buyers use gold to buy loompoints to make their own. Before long, the market becomes saturated with these weapons (look at how many DGS are on the market now) and their popularity drops off, again sometimes because of patches and sometimes for no apparent reason. You will have seen this time and time again in the past month or two: Steel Pick, Military Cleaver, Long Bow, Danish, GLA, Kuyaks.
Conclusion: Sell weapons at their height of popularity (right now, Rus Bow, Awlpike) for lots of gold. Then predict what the 'next big thing' will be and buy it for cheap - easier said than done i know.