RTP has told escportugal.pt that the announcement of the dates and the chosen host city will be done most likely before the end of July, depending on when the EBU wants to announce them too.
The candidate host cities and venues are:
Braga with
Parque de Exposições de Braga. The venue and the surrounding areas are currently being upgraded and the reconstruction is going to end in the beginning of 2018, at most in March (Might be a bit too late for Eurovision. I think this is why the dates haven't been announced yet - if Braga wins, the contest would have to be held later). It will have a capacity of 15000 people, bigger than most of the recent venues. The city has an efficient public transport system and has no problem finding a place for the press center and other secondary venues. However, the closest international airport, in Porto, is 35 min away and there isn't enough hotel beds in the city alone for everybody.
Santa Maria da Feira with
Europarque. This is a case similar to the International E
bition Center I think, as it is an open hall. It's said the capacity can be for around 10000 people. Similarly to Braga, it can hold secondary venues but the accomodation is definitely not enough, and it will need to resort to neighbouring cities like Porto, Aveiro and São João da Madeira. It's 30 min away from the Porto international airport, and it belongs to the Porto Metropolitan Area. It is the option supported by Porto Metropolitan Council.
Gondomar with
Multiusos de Gondomar. I would say this one has absolutely no chance. The venue is the smallest with capacity for only around 8000 people. It has problems for the installation of secondary venues, public transport in and out of the city and hotel acommodations. It is 20 min away from Porto's airport, and it also is in the Porto Metropolitan Council, which is supporting Santa Maria da Feira over Gondomar.
Lisbon with
MEO Arena. The obvious favourite, MEO Arena has the capacity to hold 20000 people and it is the 3rd biggest indoor arena in Europe. All the secondary venues can be located in the area around MEO Arena, known as Parque das Nações, where the Expo '98 was hosted. The area is filled with pavillions and smallar venues that can be used for anything that the EBU requires. One example is the Feira Internacional de Lisboa, right next to MEO Arena and with a capacity for 10000 people - very good to host things like the press center. Obviously there is no problem with the public transportation system nor the hotel accomodations, and the venue is only 4 minutes away from the closest international airport. It is also very close to RTP's headquarters, which can only be an advantage too.
Lisbon is the obvious choice here. The only problems might be that the EBU might consider the venue too big for Eurovision, or that the time the venue needs to be reserved for Eurovision might be too much for them, and they require a big price for that reservation. Still, all of the other host cities would require additional costs that would be bigger than this, so I think that won't be a problem.
The only competition for Lisbon would be Braga, but the upgrade of their venue is only scheduled to finish around March and that has to be too risky to choose it as the host city.
RTP's team also said that so far everything is going very smoothly, within the EBU's deadlines.