Entirely possible. First's mindset in Essex wasn't what I was accustomed to - traditionally their position on competition to do nothing and let the thing die a slow death, but in Essex they stood their corner.
In order for First Essex to massively improve their branding and standards they need to revisit how the operation functions. If they don't have the backing of all the people working there, any new initiative will only be partially successful. You can have route branding for instance, but if the controllers consider any functioning bus will suffice for the morning run out, then route branding is pointless.
Quite how you reverse that mindset I'm not sure - it is notable that First subsidiaries headed up by long serving First employees (pre Giles Fearnley) are the ones who aren't innovating and thus seeing their businesses stagnate. The innovation might not necessarily result in increased profits, but some of that will work.
Perhaps they need to ditch the 'First' identity completely and go for a new brand?
As you correctly point out, a Volvo B9TL in traditional Eastern National livery with depot plates means absolutely nothing to the customers - they want a clean, tidy bus that doesn't look like it's just come out of a war zone. They want it to turn up when the timetable says it will and they want it to tell you where it's going. None of those things are particularly hard, but it does rely on a willingness to do the job properly.
A visit to First Essex is very much on my "to do" list so this is very much a view from afar.
However, the route networks seem overly complex. I've used this examples before with the Galleywood to Hospital services in Chelmsford being 6 bph but 2 extending to Braintree and 1 to Stansted. That seems like clever use of resources but means a potential disaster for service reliability as you have to traverse the centre of Chelmsford. I might add that you have similar examples of very long services, bolted together, that must be murder to maintain in the glue pot conditions of Essex traffic, such as the 100. Then there's the endless array of service variations so that South Woodham Ferrers (nominally served by two services) has 7 service numbers. The 71 from Chelmsford to Colchester has six variations. It's bewildering, and yes, you're absolutely right that before they embark on branding, they have to get the operational nuts and bolts sorted. You cannot market an inherently poor product. I don't hold with the view that it's beyond salvation; we thought that of First as a whole, and most definitely, the First South West business. It takes good management, a lot of hard work, imagination and energy, and it helps if the local authority is on board too.
On the wider point, again I agree with you. One of the aspects of the decentralisation of First Bus and giving greater autonomy to local managers is that it has exposed those OpCos whose management doesn't appear to have the requisite skills and entrepreneurial spirit. To be honest, that was one of the great successes of Stagecoach in that you had the corporate umbrella and purchasing power, and yes, it was a very dull, standardised fleet but you also had managers with the freedom to innovate. In First (and now Arriva), there was/is the central diktat culture and that meant that you were very much reduced to turning the handle of the machine.
I think Essex and Eastern Counties have the lowest fleet age average, thanks to the loads of 2005 B7RLEs and ancient ex London Presidents respectively. Hopefully these areas get new buses, especially Norwich. South West and Scotland East are quite low too, but that’s because of their MMCs being on loan to SPS and the old Bright Bus Tour vehicles respectively
In terms of people speculating on new vehicle investment, it's probably a good indicator to look at the investment in the last few years (i.e. once the 2012-2015 sprint for PSVAR compliance had died down) and see where it's gone. IIRC, the main beneficiaries have been:
Leeds - First have a commitment (not yet fulfilled) for 284 new vehicles as part of a partnership with WYPTA and linked to new bus priorities etc
Glasgow - there is the requirement to meet a large Clean Air Zone and they have also taken advantage of various Green Bus funding to support this, plus an upgrade to the Airport service
Aberdeen - new Hydrogen vehicles again with a funding element from government
Bristol - First introduced new vehicles as operator of the metrobus scheme AND also receiving funding for the introduction of a large fleet of CNG buses and associated infrastructure, as well as new vehicles for the Airport and Wessex Water contracts
Hampshire - First introduced new vehicles on the Eclipse and Star operations to satisfy LA contractual partnerships
There has been some investment in premium routes that are commercial, I think (e.g. Eastern Counties Excel, Berkshire RailAir), and it's not an exhaustive list of every new vehicle they've received in the last 3-4 years as they'll be the odd P&R, Airport or contract service. Other than Kernow, I'm struggling to think of much "standard fleet replacement" for want of a better phrase (and arguably, Kernow was influenced by the council's ministrations with some being funded by them and transferring to Go Ahead).