BIA/Kelsey has just put out a prediction that local-mobile search will surpass local search on the PC in 2015. The following year (2016) BIA "expects mobile local search to exceed desktop local search by more than 27 billion annual queries."
There's a certain logic here -- 40% of mobile search carries a local intent (per Google) and mobile is growing faster than PC search -- but I think the crossover date is farther out than three years from now. (In developing countries it may be much sooner.) The press release doesn't mention apps and I suspect the prediction is largely or entirely about query volumes coming from the search bar on the mobile browser (which is 95% Google).
Source: Performics, 3/11
To achieve the local query volumes projected and surpass PC search equivalents by 2015, however, apps would need to be included in the calculation. Right now nobody really knows how much "search" and local search is happening in the context of apps. Nobody is actively tracking it. However, the recent Local Search Study from 15Miles, comScore and Localeze suggests that a substantial percentage of local-mobile search is happening within apps.
The survey of 4,000 US adults found that 49% of smartphone and tablet owners are using apps to find local information. I speculated that half of "local search" query volume, which might otherwise be on Google or other search engines on the PC, might be going through apps on smartphones. It's a leap but one not without some merit.
According to 2011 US survey data from Performics (chart above), 60% of mobile search users conduct fewer than 20 mobile searches per month, while 40% do 20 or more searches monthly. There are other data and surveys I could cite; this is just one. It illustrates, however, that there's a significant gap currently between PC and mobile search today. On the PC, comScore said last year that US adults conduct an average of 107 search queries per month.
If we use Google's 20% PC local search number, it would mean that in March there were roughly 3.7 billion local searches on the PC in the US. If we use Yahoo's 30% figure it would be more like 5.5 billion. The average of the two is 4.6 billion monthly local queries. (I believe these figures probably under count PC local intent search volumes.) If there are now roughly 125 million smartphone users in the US and roughly 90% of them use search, that means in any given month 112.5 million people are searching for stuff. If we assume they're all doing 20 queries a month (near the top end of the Perfomics range) that comes to 2.25 billion mobile queries monthly in the US. However only a subset of those are local.
If we use Google's 40% (of mobile search is local) figure, then roughly 900 million mobile search queries have a local intent on a monthly basis. (This number is likely higher than what's actually happening in the market given the assumption of 20 searches per month on average.) And again this doesn't account for local search queries happening in apps, which is probably hundreds of millions at least.
Indeed, "search" takes many forms on mobile devices, and much of it isn't running through a traditional search engine like Google. Yet mobile queries on Google are also growing rapidly. While overall mobile search volumes will continue to grow and while they could grow from 900 million to more than 4 or 5 billion monthly queries in three years I just don't see that happening unless we count app-based query volumes as part of the equation.