Growing forever is an interesting concept economically speaking. While of course there's an infinite amount of "stuff" to buy, arguably there could be an infinitely large (or at least indefinitely large) amount of services one could say no to in favor of Bitcoin, which would give it that indefinitely large if not infinite value potential. I would tend to say this is unlikely, if only because at some point base survival needs tend to kick in -- but hard money does tend to suck up extra value rather than encourage wasteful spending of resources in non-productive manners.

On the other hand, in fiat terms, while arguably in a mathematical sense inflation is multiplicative, it could perpetually approach while never arriving at zero. In practice, people tend to avoid fiat completely at some point, because it just gets too cumbersome to use (the paper is worth more as fire starter, or the cost to transport becomes worth more than the paper, or any other number of ways to visualize this possibility), so it does effectively reach zero due to friction.