Interesting early observations which, now that the "medium term" has arrived, seem accurate. Not sure about the longer term though: cellulose doesn't seem to be getting "scarce", and its hard to forget the old adage about hemp in apparel ("Its remarkable how little hemp it takes to ruin a good garment")
Three fibre sources, hemp, Tencel and polyester derived from recycling polyethylene terephthalate (PET) beverage bottles, are compared with respect to their suitability for use in garments and their ecological impact. In the short term, recycled polyester will be the most attractive option. In the medium term, Tencel (lyocell) cellulosic fibres will be highly successful, but hemp may be most successful in the long term as raw materials for the other products become more scarce. Hemp processing is simple and the plant grows well, but it may be difficult to limit tetrahydrocannabinol levels. Tencel has very desirable characteristics but is currently expensive to produce.
Drury K; Slater K., Text. Trends India, vol. 39, no. 3, June 1996, pp 29-33