In my opinion, I think there will be very little to no increase in most cards, certain cards will increase in value, such as the captain signatures, maybe some other various rare subsets, however most inserts will be similar to today, but harder to unload.
The way its going at the moment, the increase in value for cards will mainly be in sealed boxes/cases, and in those situations still only on certain sets. The way I look at it is use the 1995-2005 years as an example - these are now 10-20 years old and yes, there are a few cards/sets that have increased in value, but overall some have either lost value or remain fairly similar to when they were first released. Now, pre-2000 may not be a good example as thats around the time that the standard release schedule that we see today has continued, its been modified slightly along the way, but overall its pretty much the same.
There is 1 series I am interested to see how it goes in the future is the newish future force draft release, I think these may be in high demand for future skilled players, but again, its such a lottery shot, as it will only likely be big superstars that are of interest, I mean how many #1 draft picks turn out to be superstars...