Could Democrats regain control of the US Senate in 2020 if they lose seats in 2018?

Let's say in 2018- Democrats come up short in Republican held seats in AZ,NV,TN,and TX and lose ND,MO,IN,and FL. They will end up with 45 seats.
Democrats guide to regaining control of the US Senate in 2020 is winning 7 Republican held seats.
AZ special- Gallego-D is a stronger candidate than Sinema-D and the Republican nominee will be more right-wing than McSally-R.
CO- Neguse-D could be the first black US Senator from CO and Duran-D could be the first female US Senator from CO.
GA- Tomlinson-D could replicate Abrams-D guide to victory in GA.
ME- Gideon-D will be the first Indian US Senator from ME.
MT- Bullock-D
NC- Foxx-D would be the first Black US Senator from NC.
WV- Ojeda-D if he wins or narrowly loses.

AL is the only Democratic held US Senate seat up in 2020 that is likely to flip.