F1 teams can develop engines in season

I don't really see any advantage to be gained. They are still restricted in what they can change but they have been allowed more time to introduce the changes. If they knew what was wrong with their PU then they would want to introduce the changes as soon as possible, like before the first race. Questioning the rule book seems like desperation on behalf of Ferrari and Renault who don't seem to know what to change. They must be hoping for some sort of “eureka” moment half way through the season.

As for Honda – if they listened to the utter nonsense that MA frequently spouted out then they will be trying to use a PU without Control Electronics.

It's not just about the PU, the aero is also a massive factor and then the drivers and Ferrari are fooked

It's blatantly unfair on Honda to insist they homologate their PU at the end of February when that isn't specifically in the regs but allow other manufacturers to homologate their 2015 PU whenever they want.
However it's not as big a deal as some are making out as there would be huge disadvantages to delaying homologation, e.g:
the competitive disadvantage of running old spec PUs;
the difficulties of having to introduce the 2015 spec to all teams/drivers at the same time as once the 2015 spec is introduced the 2014 spec can't be used even in practice;
the effect on aero development by the chassis having to suit both 2014 and 2015 PUs, possibly resulting in a b-car being needed.

I think it will only happen if Renault or Ferrari make a major mistake that they only find during preseason testing or if they concede that they are so far behind that they are better giving up on 2015 and effectively rolling over the tokens for a year by delaying homologation until December.

All teams knew about the rule changes and I am amazed Renault who pushed really hard for these changes, we know that the clowns at Ferrari would struggle but this issue for Redbull has a lot to do with their general arrangement and packaging of the car.

This sounds crazy but I actually think Honda pose the biggest threat to Mercedes. The other teams are behind and Mercedes will make improvements at the same rate and if Mclaren can sort out the car design, they will be a threat

I completely agree.

With Prodromou working on the aerodynamics and Honda providing an engine that's been in the works longer than the others, McLaren could be serious contenders next year.