The 'specification of new services' was already shown in detail in something called train service requirement 2, (TSR2), available on the DfT website:
https://www.gov.uk/government/publications/east-anglia-franchise-2015-invitation-to-tender
But TSR2 only commences at May 2019 timetable change. Something like the status quo will operate for the first period of the franchise, TSR1.
It is unheard of for there to be significant immediate changes on first day of a new franchisee, as new/extra rolling stock, additional train crew, and sometimes additional infrastructure all have such significant lead times.
Also, don't forget that when DfT typically spin these announcements, that '180 new services' counts each 'service' in two separate directions, and separates out different days. The obvious detail from the Stakeholder briefing is that it is 90 Mon - Sat, and a separate 90 on Sundays.
https://www.gov.uk/government/uploa...e/481392/east-anglia-stakeholder-briefing.pdf
So it already looks like much less than the headline figure. Then some 'new services' may be increased frequencies, or just relatively short extensions.