Top-flight clubs on Monday gave their "unanimous backing" to proposals for a revamped 12-12-18 league structure. Doncaster revealed consensus had been achieved at a meeting of the 12 clubs at Hampden and the plans will be discussed by Scottish Football League clubs on Thursday.
He said: "Ultimately, this is a larger league. It will involve more teams and it will involve play-offs so there will be a lot more teams involved in promotion and relegation. I think it will drive excitement and will drive interest."
If given the green-light by SFL clubs, the new format could be in place for next season, and Doncaster added: "There is a package of measures in place, which is being discussed at length with the SFL board and with the SFA, and one of those measures is clearly the start for next season."
Asked what the alternative is should the proposals fall through, he said: "It's not been discussed and I don't want to speculate about what the future might hold. We've got a mood for a change, a spirit for change, and we've got consensus within the SPL clubs around a model that can deliver all these positive elements."
Hearts managing director David Southern was also encouraged by Monday's talks, saying: "It was a very good meeting, a very positive meeting and another step in the right direction for Scottish football.
"We do believe it can make the game much more attractive. If we can get further on in the process, we might actually have a bright future in the game in this country. It's going to reinvigorate and refresh the game."
Southern believes fans who are sceptical about the plans now will be won over eventually.
He said: "We believe it will attract more supporters in time, when supporters are given a chance to actually understand the model fully. It will create extra competition, there will be very few meaningless games, it will be a truly competitive league set-up across the entire game in the country.
"It's very important that we explain very clearly the pros and cons to this system. It's not fool-proof, it's not perfect, but it's a step in the right direction. We've all got a duty now to explain to our supporters the benefits of this system."
- Sports & Recreation