I bet that at least half of the 6 Merc-engine cars will use only 3 engines for the season. Honda is getting much closer on power, but in terms of total package (power, fuel-econ/weight, reliability during races, grid penalties due to various failures and pre-emptive changes) Merc will be very hard to beat. Ferrari essentially matched Merc on total power last year but was out of the championship picture by the last race due to not matching the total package.
I really like Wazari's earlier comment about Honda doing some aggressive new combustion strategy because that would be the only way to get ahead of Merc. Too many comments from Ferrari and Renault describe how they hope to catch up, with no mention of seriously being better.

