It will, but not by much and not very fast.
Of the people that play runescape, only a small percentage of them will ever spend money at all, and an even smaller amount will spend more than 10$ .
Beyond on that, Mobile is not really meant to be a luxury for existing player (to add a moot point while i'm here, people who are already playing the game have either bought enough, buying, or will never buy. having little to no impact.) It is meant to attract a whole new audience who will have to first expose a long term interest into the game before investing anything into it. In addition to a new audience, it's a whole new platform. Mobile devices. Unless currency is being offered in game like the typical app store, they're not going to search the web or gold. The only new audience that will be spending on gold will be the bond buyers (This has little to no impact) or the poor individuals blindly buying into the spam bots in lumbridge for extremely overpriced retail sites. The majority of new players will be ages 8-12. Of course they have no source of income so their gold buying is extremely limited.
In the long term we will see items sharply rise in price and then hit new all time lows.